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BIND 9 Security Considerations"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr><th colspan="3" align="center">Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</th></tr> <tr> <td width="20%" align="left"> <a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td> <th width="60%" align="center"> </th> <td width="20%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a> </td> </tr> </table> <hr> </div> <div class="chapter" lang="en"> <div class="titlepage"><div><div><h2 class="title"> <a name="Bv9ARM.ch06"></a>Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</h2></div></div></div> <div class="toc"> <p><b>Table of Contents</b></p> <dl> <dt><span class="sect1"><a href="Bv9ARM.ch06.html#configuration_file_elements">Configuration File Elements</a></span></dt> <dd><dl> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#address_match_lists">Address Match Lists</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575672">Comment Syntax</a></span></dt> </dl></dd> <dt><span class="sect1"><a href="Bv9ARM.ch06.html#Configuration_File_Grammar">Configuration File Grammar</a></span></dt> <dd><dl> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576157"><span><strong class="command">acl</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#acl"><span><strong class="command">acl</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576326"><span><strong class="command">controls</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage"><span><strong class="command">controls</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576672"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576686"><span><strong class="command">include</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576709"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576730"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2576870"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577064"><span><strong class="command">logging</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578270"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578343"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578406"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578518"><span><strong class="command">masters</strong></span> Statement Definition and Usage </a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578533"><span><strong class="command">options</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#options"><span><strong class="command">options</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_grammar"><span><strong class="command">server</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_definition_and_usage"><span><strong class="command">server</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2586290"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2586338"><span><strong class="command">trusted-keys</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#view_statement_grammar"><span><strong class="command">view</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2586420"><span><strong class="command">view</strong></span> Statement Definition and Usage</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span><strong class="command">zone</strong></span> Statement Grammar</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2587635"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt> </dl></dd> <dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2589173">Zone File</a></span></dt> <dd><dl> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them">Types of Resource Records and When to Use Them</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2590605">Discussion of MX Records</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591102">Inverse Mapping in IPv4</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591208">Other Zone File Directives</a></span></dt> <dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591377"><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</a></span></dt> </dl></dd> </dl> </div> <p><acronym class="acronym">BIND</acronym> 9 configuration is broadly similar to <acronym class="acronym">BIND</acronym> 8; however, there are a few new areas of configuration, such as views. <acronym class="acronym">BIND</acronym> 8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym> 9, although more complex configurations should be reviewed to check if they can be more efficiently implemented using the new features found in <acronym class="acronym">BIND</acronym> 9.</p> <p><acronym class="acronym">BIND</acronym> 4 configuration files can be converted to the new format using the shell script <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>.</p> <div class="sect1" lang="en"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div> <p>Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration file documentation:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="varname">acl_name</code></p></td> <td><p>The name of an <code class="varname">address_match_list</code> as defined by the <span><strong class="command">acl</strong></span> statement.</p></td> </tr> <tr> <td><p><code class="varname">address_match_list</code></p></td> <td><p>A list of one or more <code class="varname">ip_addr</code>, <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>, or <code class="varname">acl_name</code> elements, see <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a>.</p></td> </tr> <tr> <td><p><code class="varname">domain_name</code></p></td> <td><p>A quoted string which will be used as a DNS name, for example "<code class="literal">my.test.domain</code>".</p></td> </tr> <tr> <td><p><code class="varname">dotted_decimal</code></p></td> <td><p>One to four integers valued 0 through 255 separated by dots (`.'), such as <span><strong class="command">123</strong></span>, <span><strong class="command">45.67</strong></span> or <span><strong class="command">89.123.45.67</strong></span>.</p></td> </tr> <tr> <td><p><code class="varname">ip4_addr</code></p></td> <td><p>An IPv4 address with exactly four elements in <code class="varname">dotted_decimal</code> notation.</p></td> </tr> <tr> <td><p><code class="varname">ip6_addr</code></p></td> <td><p>An IPv6 address, such as <span><strong class="command">2001:db8::1234</strong></span>. IPv6 scoped addresses that have ambiguity on their scope zones must be disambiguated by an appropriate zone ID with the percent character (`%') as delimiter. It is strongly recommended to use string zone names rather than numeric identifiers, in order to be robust against system configuration changes. However, since there is no standard mapping for such names and identifier values, currently only interface names as link identifiers are supported, assuming one-to-one mapping between interfaces and links. For example, a link-local address <span><strong class="command">fe80::1</strong></span> on the link attached to the interface <span><strong class="command">ne0</strong></span> can be specified as <span><strong class="command">fe80::1%ne0</strong></span>. Note that on most systems link-local addresses always have the ambiguity, and need to be disambiguated.</p></td> </tr> <tr> <td><p><code class="varname">ip_addr</code></p></td> <td><p>An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.</p></td> </tr> <tr> <td><p><code class="varname">ip_port</code></p></td> <td><p>An IP port <code class="varname">number</code>. <code class="varname">number</code> is limited to 0 through 65535, with values below 1024 typically restricted to use by processes running as root. In some cases, an asterisk (`*') character can be used as a placeholder to select a random high-numbered port.</p></td> </tr> <tr> <td><p><code class="varname">ip_prefix</code></p></td> <td><p>An IP network specified as an <code class="varname">ip_addr</code>, followed by a slash (`/') and then the number of bits in the netmask. Trailing zeros in a <code class="varname">ip_addr</code> may omitted. For example, <span><strong class="command">127/8</strong></span> is the network <span><strong class="command">127.0.0.0</strong></span> with netmask <span><strong class="command">255.0.0.0</strong></span> and <span><strong class="command">1.2.3.0/28</strong></span> is network <span><strong class="command">1.2.3.0</strong></span> with netmask <span><strong class="command">255.255.255.240</strong></span>.</p></td> </tr> <tr> <td><p><code class="varname">key_id</code></p></td> <td><p>A <code class="varname">domain_name</code> representing the name of a shared key, to be used for transaction security.</p></td> </tr> <tr> <td><p><code class="varname">key_list</code></p></td> <td><p>A list of one or more <code class="varname">key_id</code>s, separated by semicolons and ending with a semicolon.</p></td> </tr> <tr> <td><p><code class="varname">number</code></p></td> <td><p>A non-negative 32-bit integer (i.e., a number between 0 and 4294967295, inclusive). Its acceptable value might further be limited by the context in which it is used.</p></td> </tr> <tr> <td><p><code class="varname">path_name</code></p></td> <td><p>A quoted string which will be used as a pathname, such as <code class="filename">zones/master/my.test.domain</code>.</p></td> </tr> <tr> <td><p><code class="varname">size_spec</code></p></td> <td> <p>A number, the word <strong class="userinput"><code>unlimited</code></strong>, or the word <strong class="userinput"><code>default</code></strong>.</p> <p> An <code class="varname">unlimited</code> <code class="varname">size_spec</code> requests unlimited use, or the maximum available amount. A <code class="varname">default size_spec</code> uses the limit that was in force when the server was started.</p> <p>A <code class="varname">number</code> can optionally be followed by a scaling factor: <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong> for kilobytes, <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong> for megabytes, and <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong> for gigabytes, which scale by 1024, 1024*1024, and 1024*1024*1024 respectively.</p> <p>The value must be representable as a 64-bit unsigned integer (0 to 18446744073709551615, inclusive). Using <code class="varname">unlimited</code> is the best way to safely set a really large number.</p> </td> </tr> <tr> <td><p><code class="varname">yes_or_no</code></p></td> <td><p>Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>. The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are also accepted, as are the numbers <strong class="userinput"><code>1</code></strong> and <strong class="userinput"><code>0</code></strong>.</p></td> </tr> <tr> <td><p><code class="varname">dialup_option</code></p></td> <td><p>One of <strong class="userinput"><code>yes</code></strong>, <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>, <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or <strong class="userinput"><code>passive</code></strong>. When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong> are restricted to slave and stub zones.</p></td> </tr> </tbody> </table></div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="address_match_lists"></a>Address Match Lists</h3></div></div></div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2575552"></a>Syntax</h4></div></div></div> <pre class="programlisting"><code class="varname">address_match_list</code> = address_match_list_element ; [<span class="optional"> address_match_list_element; ... </span>] <code class="varname">address_match_list_element</code> = [<span class="optional"> ! </span>] (ip_address [<span class="optional">/length</span>] | key key_id | acl_name | { address_match_list } ) </pre> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2575578"></a>Definition and Usage</h4></div></div></div> <p>Address match lists are primarily used to determine access control for various server operations. They are also used in the <span><strong class="command">listen-on</strong></span> and <span><strong class="command">sortlist</strong></span> statements. The elements which constitute an address match list can be any of the following:</p> <div class="itemizedlist"><ul type="disc"> <li>an IP address (IPv4 or IPv6)</li> <li>an IP prefix (in `/' notation)</li> <li>a key ID, as defined by the <span><strong class="command">key</strong></span> statement</li> <li>the name of an address match list defined with the <span><strong class="command">acl</strong></span> statement</li> <li>a nested address match list enclosed in braces</li> </ul></div> <p>Elements can be negated with a leading exclamation mark (`!'), and the match list names "any", "none", "localhost", and "localnets" are predefined. More information on those names can be found in the description of the acl statement.</p> <p>The addition of the key clause made the name of this syntactic element something of a misnomer, since security keys can be used to validate access without regard to a host or network address. Nonetheless, the term "address match list" is still used throughout the documentation.</p> <p>When a given IP address or prefix is compared to an address match list, the list is traversed in order until an element matches. The interpretation of a match depends on whether the list is being used for access control, defining listen-on ports, or in a sortlist, and whether the element was negated.</p> <p>When used as an access control list, a non-negated match allows access and a negated match denies access. If there is no match, access is denied. The clauses <span><strong class="command">allow-notify</strong></span>, <span><strong class="command">allow-query</strong></span>, <span><strong class="command">allow-transfer</strong></span>, <span><strong class="command">allow-update</strong></span>, <span><strong class="command">allow-update-forwarding</strong></span>, and <span><strong class="command">blackhole</strong></span> all use address match lists this. Similarly, the listen-on option will cause the server to not accept queries on any of the machine's addresses which do not match the list.</p> <p>Because of the first-match aspect of the algorithm, an element that defines a subset of another element in the list should come before the broader element, regardless of whether either is negated. For example, in <span><strong class="command">1.2.3/24; ! 1.2.3.13;</strong></span> the 1.2.3.13 element is completely useless because the algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24 element. Using <span><strong class="command">! 1.2.3.13; 1.2.3/24</strong></span> fixes that problem by having 1.2.3.13 blocked by the negation but all other 1.2.3.* hosts fall through.</p> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2575672"></a>Comment Syntax</h3></div></div></div> <p>The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for comments to appear anywhere that white space may appear in a <acronym class="acronym">BIND</acronym> configuration file. To appeal to programmers of all kinds, they can be written in the C, C++, or shell/perl style.</p> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2575687"></a>Syntax</h4></div></div></div> <pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre> <p> </p> <pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre> <p> </p> <pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells and perl</pre> <p> </p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2575716"></a>Definition and Usage</h4></div></div></div> <p>Comments may appear anywhere that white space may appear in a <acronym class="acronym">BIND</acronym> configuration file.</p> <p>C-style comments start with the two characters /* (slash, star) and end with */ (star, slash). Because they are completely delimited with these characters, they can be used to comment only a portion of a line or to span multiple lines.</p> <p>C-style comments cannot be nested. For example, the following is not valid because the entire comment ends with the first */:</p> <pre class="programlisting">/* This is the start of a comment. This is still part of the comment. /* This is an incorrect attempt at nesting a comment. */ This is no longer in any comment. */ </pre> <p>C++-style comments start with the two characters // (slash, slash) and continue to the end of the physical line. They cannot be continued across multiple physical lines; to have one logical comment span multiple lines, each line must use the // pair.</p> <p>For example:</p> <pre class="programlisting">// This is the start of a comment. The next line // is a new comment, even though it is logically // part of the previous comment. </pre> <p>Shell-style (or perl-style, if you prefer) comments start with the character <code class="literal">#</code> (number sign) and continue to the end of the physical line, as in C++ comments.</p> <p>For example:</p> <pre class="programlisting"># This is the start of a comment. The next line # is a new comment, even though it is logically # part of the previous comment. </pre> <p> </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Warning</h3> <p>You cannot use the semicolon (`;') character to start a comment such as you would in a zone file. The semicolon indicates the end of a configuration statement.</p> </div> </div> </div> </div> <div class="sect1" lang="en"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div> <p>A <acronym class="acronym">BIND</acronym> 9 configuration consists of statements and comments. Statements end with a semicolon. Statements and comments are the only elements that can appear without enclosing braces. Many statements contain a block of sub-statements, which are also terminated with a semicolon.</p> <p>The following statements are supported:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">acl</strong></span></p></td> <td><p>defines a named IP address matching list, for access control and other uses.</p></td> </tr> <tr> <td><p><span><strong class="command">controls</strong></span></p></td> <td><p>declares control channels to be used by the <span><strong class="command">rndc</strong></span> utility.</p></td> </tr> <tr> <td><p><span><strong class="command">include</strong></span></p></td> <td><p>includes a file.</p></td> </tr> <tr> <td><p><span><strong class="command">key</strong></span></p></td> <td><p>specifies key information for use in authentication and authorization using TSIG.</p></td> </tr> <tr> <td><p><span><strong class="command">logging</strong></span></p></td> <td><p>specifies what the server logs, and where the log messages are sent.</p></td> </tr> <tr> <td><p><span><strong class="command">lwres</strong></span></p></td> <td><p>configures <span><strong class="command">named</strong></span> to also act as a light-weight resolver daemon (<span><strong class="command">lwresd</strong></span>).</p></td> </tr> <tr> <td><p><span><strong class="command">masters</strong></span></p></td> <td><p>defines a named masters list for inclusion in stub and slave zone masters clauses.</p></td> </tr> <tr> <td><p><span><strong class="command">options</strong></span></p></td> <td><p>controls global server configuration options and sets defaults for other statements.</p></td> </tr> <tr> <td><p><span><strong class="command">server</strong></span></p></td> <td><p>sets certain configuration options on a per-server basis.</p></td> </tr> <tr> <td><p><span><strong class="command">trusted-keys</strong></span></p></td> <td><p>defines trusted DNSSEC keys.</p></td> </tr> <tr> <td><p><span><strong class="command">view</strong></span></p></td> <td><p>defines a view.</p></td> </tr> <tr> <td><p><span><strong class="command">zone</strong></span></p></td> <td><p>defines a zone.</p></td> </tr> </tbody> </table></div> <p>The <span><strong class="command">logging</strong></span> and <span><strong class="command">options</strong></span> statements may only occur once per configuration.</p> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576157"></a><span><strong class="command">acl</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting"><span><strong class="command">acl</strong></span> acl-name { address_match_list }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="acl"></a><span><strong class="command">acl</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">acl</strong></span> statement assigns a symbolic name to an address match list. It gets its name from a primary use of address match lists: Access Control Lists (ACLs).</p> <p>Note that an address match list's name must be defined with <span><strong class="command">acl</strong></span> before it can be used elsewhere; no forward references are allowed.</p> <p>The following ACLs are built-in:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">any</strong></span></p></td> <td><p>Matches all hosts.</p></td> </tr> <tr> <td><p><span><strong class="command">none</strong></span></p></td> <td><p>Matches no hosts.</p></td> </tr> <tr> <td><p><span><strong class="command">localhost</strong></span></p></td> <td><p>Matches the IPv4 and IPv6 addresses of all network interfaces on the system.</p></td> </tr> <tr> <td><p><span><strong class="command">localnets</strong></span></p></td> <td><p>Matches any host on an IPv4 or IPv6 network for which the system has an interface. Some systems do not provide a way to determine the prefix lengths of local IPv6 addresses. In such a case, <span><strong class="command">localnets</strong></span> only matches the local IPv6 addresses, just like <span><strong class="command">localhost</strong></span>. </p></td> </tr> </tbody> </table></div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576326"></a><span><strong class="command">controls</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting"><span><strong class="command">controls</strong></span> { inet ( ip_addr | * ) [<span class="optional"> port ip_port </span>] allow { <em class="replaceable"><code> address_match_list </code></em> } keys { <em class="replaceable"><code> key_list </code></em> }; [<span class="optional"> inet ...; </span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="controls_statement_definition_and_usage"></a><span><strong class="command">controls</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">controls</strong></span> statement declares control channels to be used by system administrators to control the operation of the name server. These control channels are used by the <span><strong class="command">rndc</strong></span> utility to send commands to and retrieve non-DNS results from a name server.</p> <p>An <span><strong class="command">inet</strong></span> control channel is a TCP socket listening at the specified <span><strong class="command">ip_port</strong></span> on the specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is interpreted as the IPv4 wildcard address; connections will be accepted on any of the system's IPv4 addresses. To listen on the IPv6 wildcard address, use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>. If you will only use <span><strong class="command">rndc</strong></span> on the local host, using the loopback address (<code class="literal">127.0.0.1</code> or <code class="literal">::1</code>) is recommended for maximum security. </p> <p> If no port is specified, port 953 is used. The asterisk "<code class="literal">*</code>" cannot be used for <span><strong class="command">ip_port</strong></span>.</p> <p>The ability to issue commands over the control channel is restricted by the <span><strong class="command">allow</strong></span> and <span><strong class="command">keys</strong></span> clauses. Connections to the control channel are permitted based on the <span><strong class="command">address_match_list</strong></span>. This is for simple IP address based filtering only; any <span><strong class="command">key_id</strong></span> elements of the <span><strong class="command">address_match_list</strong></span> are ignored. </p> <p>The primary authorization mechanism of the command channel is the <span><strong class="command">key_list</strong></span>, which contains a list of <span><strong class="command">key_id</strong></span>s. Each <span><strong class="command">key_id</strong></span> in the <span><strong class="command">key_list</strong></span> is authorized to execute commands over the control channel. See <a href="Bv9ARM.ch03.html#rndc">Remote Name Daemon Control application</a> in <a href="Bv9ARM.ch03.html#admin_tools" title="Administrative Tools">the section called “Administrative Tools”</a>) for information about configuring keys in <span><strong class="command">rndc</strong></span>.</p> <p> If no <span><strong class="command">controls</strong></span> statement is present, <span><strong class="command">named</strong></span> will set up a default control channel listening on the loopback address 127.0.0.1 and its IPv6 counterpart ::1. In this case, and also when the <span><strong class="command">controls</strong></span> statement is present but does not have a <span><strong class="command">keys</strong></span> clause, <span><strong class="command">named</strong></span> will attempt to load the command channel key from the file <code class="filename">rndc.key</code> in <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code> was specified as when <acronym class="acronym">BIND</acronym> was built). To create a <code class="filename">rndc.key</code> file, run <strong class="userinput"><code>rndc-confgen -a</code></strong>. </p> <p>The <code class="filename">rndc.key</code> feature was created to ease the transition of systems from <acronym class="acronym">BIND</acronym> 8, which did not have digital signatures on its command channel messages and thus did not have a <span><strong class="command">keys</strong></span> clause. It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8 configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged, and still have <span><strong class="command">rndc</strong></span> work the same way <span><strong class="command">ndc</strong></span> worked in BIND 8, simply by executing the command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is installed. </p> <p> Since the <code class="filename">rndc.key</code> feature is only intended to allow the backward-compatible usage of <acronym class="acronym">BIND</acronym> 8 configuration files, this feature does not have a high degree of configurability. You cannot easily change the key name or the size of the secret, so you should make a <code class="filename">rndc.conf</code> with your own key if you wish to change those things. The <code class="filename">rndc.key</code> file also has its permissions set such that only the owner of the file (the user that <span><strong class="command">named</strong></span> is running as) can access it. If you desire greater flexibility in allowing other users to access <span><strong class="command">rndc</strong></span> commands, then you need to create a <code class="filename">rndc.conf</code> file and make it group readable by a group that contains the users who should have access.</p> <p>The UNIX control channel type of <acronym class="acronym">BIND</acronym> 8 is not supported in <acronym class="acronym">BIND</acronym> 9.0, <acronym class="acronym">BIND</acronym> 9.1, <acronym class="acronym">BIND</acronym> 9.2 and <acronym class="acronym">BIND</acronym> 9.3. If it is present in the controls statement from a <acronym class="acronym">BIND</acronym> 8 configuration file, it is ignored and a warning is logged.</p> <p> To disable the command channel, use an empty <span><strong class="command">controls</strong></span> statement: <span><strong class="command">controls { };</strong></span>. </p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576672"></a><span><strong class="command">include</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">include <em class="replaceable"><code>filename</code></em>;</pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576686"></a><span><strong class="command">include</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">include</strong></span> statement inserts the specified file at the point where the <span><strong class="command">include</strong></span> statement is encountered. The <span><strong class="command">include</strong></span> statement facilitates the administration of configuration files by permitting the reading or writing of some things but not others. For example, the statement could include private keys that are readable only by the name server.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576709"></a><span><strong class="command">key</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">key <em class="replaceable"><code>key_id</code></em> { algorithm <em class="replaceable"><code>string</code></em>; secret <em class="replaceable"><code>string</code></em>; }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576730"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">key</strong></span> statement defines a shared secret key for use with TSIG (see <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>) or the command channel (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and Usage”</a>). </p> <p> The <span><strong class="command">key</strong></span> statement can occur at the top level of the configuration file or inside a <span><strong class="command">view</strong></span> statement. Keys defined in top-level <span><strong class="command">key</strong></span> statements can be used in all views. Keys intended for use in a <span><strong class="command">controls</strong></span> statement (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and Usage”</a>) must be defined at the top level. </p> <p>The <em class="replaceable"><code>key_id</code></em>, also known as the key name, is a domain name uniquely identifying the key. It can be used in a <span><strong class="command">server</strong></span> statement to cause requests sent to that server to be signed with this key, or in address match lists to verify that incoming requests have been signed with a key matching this name, algorithm, and secret.</p> <p>The <em class="replaceable"><code>algorithm_id</code></em> is a string that specifies a security/authentication algorithm. The only algorithm currently supported with TSIG authentication is <code class="literal">hmac-md5</code>. The <em class="replaceable"><code>secret_string</code></em> is the secret to be used by the algorithm, and is treated as a base-64 encoded string.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2576870"></a><span><strong class="command">logging</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting"><span><strong class="command">logging</strong></span> { [ <span><strong class="command">channel</strong></span> <em class="replaceable"><code>channel_name</code></em> { ( <span><strong class="command">file</strong></span> <em class="replaceable"><code>path name</code></em> [ <span><strong class="command">versions</strong></span> ( <em class="replaceable"><code>number</code></em> | <code class="literal">unlimited</code> ) ] [ <span><strong class="command">size</strong></span> <em class="replaceable"><code>size spec</code></em> ] | <span><strong class="command">syslog</strong></span> <em class="replaceable"><code>syslog_facility</code></em> | <span><strong class="command">stderr</strong></span> | <span><strong class="command">null</strong></span> ); [ <span><strong class="command">severity</strong></span> (<code class="option">critical</code> | <code class="option">error</code> | <code class="option">warning</code> | <code class="option">notice</code> | <code class="option">info</code> | <code class="option">debug</code> [ <em class="replaceable"><code>level</code></em> ] | <code class="option">dynamic</code> ); ] [ <span><strong class="command">print-category</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] [ <span><strong class="command">print-severity</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] [ <span><strong class="command">print-time</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] }; ] [ <span><strong class="command">category</strong></span> <em class="replaceable"><code>category_name</code></em> { <em class="replaceable"><code>channel_name</code></em> ; [ <em class="replaceable"><code>channel_nam</code></em>e ; ... ] }; ] ... }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2577064"></a><span><strong class="command">logging</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">logging</strong></span> statement configures a wide variety of logging options for the name server. Its <span><strong class="command">channel</strong></span> phrase associates output methods, format options and severity levels with a name that can then be used with the <span><strong class="command">category</strong></span> phrase to select how various classes of messages are logged.</p> <p>Only one <span><strong class="command">logging</strong></span> statement is used to define as many channels and categories as are wanted. If there is no <span><strong class="command">logging</strong></span> statement, the logging configuration will be:</p> <pre class="programlisting">logging { category default { default_syslog; default_debug; }; category unmatched { null; }; }; </pre> <p>In <acronym class="acronym">BIND</acronym> 9, the logging configuration is only established when the entire configuration file has been parsed. In <acronym class="acronym">BIND</acronym> 8, it was established as soon as the <span><strong class="command">logging</strong></span> statement was parsed. When the server is starting up, all logging messages regarding syntax errors in the configuration file go to the default channels, or to standard error if the "<code class="option">-g</code>" option was specified.</p> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2577116"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div> <p>All log output goes to one or more <span class="emphasis"><em>channels</em></span>; you can make as many of them as you want.</p> <p>Every channel definition must include a destination clause that says whether messages selected for the channel go to a file, to a particular syslog facility, to the standard error stream, or are discarded. It can optionally also limit the message severity level that will be accepted by the channel (the default is <span><strong class="command">info</strong></span>), and whether to include a <span><strong class="command">named</strong></span>-generated time stamp, the category name and/or severity level (the default is not to include any).</p> <p>The <span><strong class="command">null</strong></span> destination clause causes all messages sent to the channel to be discarded; in that case, other options for the channel are meaningless.</p> <p>The <span><strong class="command">file</strong></span> destination clause directs the channel to a disk file. It can include limitations both on how large the file is allowed to become, and how many versions of the file will be saved each time the file is opened.</p> <p>If you use the <span><strong class="command">versions</strong></span> log file option, then <span><strong class="command">named</strong></span> will retain that many backup versions of the file by renaming them when opening. For example, if you choose to keep three old versions of the file <code class="filename">lamers.log</code>, then just before it is opened <code class="filename">lamers.log.1</code> is renamed to <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is renamed to <code class="filename">lamers.log.0</code>. You can say <span><strong class="command">versions unlimited</strong></span> to not limit the number of versions. If a <span><strong class="command">size</strong></span> option is associated with the log file, then renaming is only done when the file being opened exceeds the indicated size. No backup versions are kept by default; any existing log file is simply appended.</p> <p>The <span><strong class="command">size</strong></span> option for files is used to limit log growth. If the file ever exceeds the size, then <span><strong class="command">named</strong></span> will stop writing to the file unless it has a <span><strong class="command">versions</strong></span> option associated with it. If backup versions are kept, the files are rolled as described above and a new one begun. If there is no <span><strong class="command">versions</strong></span> option, no more data will be written to the log until some out-of-band mechanism removes or truncates the log to less than the maximum size. The default behavior is not to limit the size of the file.</p> <p>Example usage of the <span><strong class="command">size</strong></span> and <span><strong class="command">versions</strong></span> options:</p> <pre class="programlisting">channel an_example_channel { file "example.log" versions 3 size 20m; print-time yes; print-category yes; }; </pre> <p>The <span><strong class="command">syslog</strong></span> destination clause directs the channel to the system log. Its argument is a syslog facility as described in the <span><strong class="command">syslog</strong></span> man page. Known facilities are <span><strong class="command">kern</strong></span>, <span><strong class="command">user</strong></span>, <span><strong class="command">mail</strong></span>, <span><strong class="command">daemon</strong></span>, <span><strong class="command">auth</strong></span>, <span><strong class="command">syslog</strong></span>, <span><strong class="command">lpr</strong></span>, <span><strong class="command">news</strong></span>, <span><strong class="command">uucp</strong></span>, <span><strong class="command">cron</strong></span>, <span><strong class="command">authpriv</strong></span>, <span><strong class="command">ftp</strong></span>, <span><strong class="command">local0</strong></span>, <span><strong class="command">local1</strong></span>, <span><strong class="command">local2</strong></span>, <span><strong class="command">local3</strong></span>, <span><strong class="command">local4</strong></span>, <span><strong class="command">local5</strong></span>, <span><strong class="command">local6</strong></span> and <span><strong class="command">local7</strong></span>, however not all facilities are supported on all operating systems. How <span><strong class="command">syslog</strong></span> will handle messages sent to this facility is described in the <span><strong class="command">syslog.conf</strong></span> man page. If you have a system which uses a very old version of <span><strong class="command">syslog</strong></span> that only uses two arguments to the <span><strong class="command">openlog()</strong></span> function, then this clause is silently ignored.</p> <p>The <span><strong class="command">severity</strong></span> clause works like <span><strong class="command">syslog</strong></span>'s "priorities", except that they can also be used if you are writing straight to a file rather than using <span><strong class="command">syslog</strong></span>. Messages which are not at least of the severity level given will not be selected for the channel; messages of higher severity levels will be accepted.</p> <p>If you are using <span><strong class="command">syslog</strong></span>, then the <span><strong class="command">syslog.conf</strong></span> priorities will also determine what eventually passes through. For example, defining a channel facility and severity as <span><strong class="command">daemon</strong></span> and <span><strong class="command">debug</strong></span> but only logging <span><strong class="command">daemon.warning</strong></span> via <span><strong class="command">syslog.conf</strong></span> will cause messages of severity <span><strong class="command">info</strong></span> and <span><strong class="command">notice</strong></span> to be dropped. If the situation were reversed, with <span><strong class="command">named</strong></span> writing messages of only <span><strong class="command">warning</strong></span> or higher, then <span><strong class="command">syslogd</strong></span> would print all messages it received from the channel.</p> <p>The <span><strong class="command">stderr</strong></span> destination clause directs the channel to the server's standard error stream. This is intended for use when the server is running as a foreground process, for example when debugging a configuration.</p> <p>The server can supply extensive debugging information when it is in debugging mode. If the server's global debug level is greater than zero, then debugging mode will be active. The global debug level is set either by starting the <span><strong class="command">named</strong></span> server with the <code class="option">-d</code> flag followed by a positive integer, or by running <span><strong class="command">rndc trace</strong></span>. The global debug level can be set to zero, and debugging mode turned off, by running <span><strong class="command">rndc notrace</strong></span>. All debugging messages in the server have a debug level, and higher debug levels give more detailed output. Channels that specify a specific debug severity, for example:</p> <pre class="programlisting">channel specific_debug_level { file "foo"; severity debug 3; }; </pre> <p>will get debugging output of level 3 or less any time the server is in debugging mode, regardless of the global debugging level. Channels with <span><strong class="command">dynamic</strong></span> severity use the server's global debug level to determine what messages to print.</p> <p>If <span><strong class="command">print-time</strong></span> has been turned on, then the date and time will be logged. <span><strong class="command">print-time</strong></span> may be specified for a <span><strong class="command">syslog</strong></span> channel, but is usually pointless since <span><strong class="command">syslog</strong></span> also prints the date and time. If <span><strong class="command">print-category</strong></span> is requested, then the category of the message will be logged as well. Finally, if <span><strong class="command">print-severity</strong></span> is on, then the severity level of the message will be logged. The <span><strong class="command">print-</strong></span> options may be used in any combination, and will always be printed in the following order: time, category, severity. Here is an example where all three <span><strong class="command">print-</strong></span> options are on:</p> <p><code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code></p> <p>There are four predefined channels that are used for <span><strong class="command">named</strong></span>'s default logging as follows. How they are used is described in <a href="Bv9ARM.ch06.html#the_category_phrase" title="The category Phrase">the section called “The <span><strong class="command">category</strong></span> Phrase”</a>. </p> <pre class="programlisting">channel default_syslog { syslog daemon; // send to syslog's daemon // facility severity info; // only send priority info // and higher }; channel default_debug { file "named.run"; // write to named.run in // the working directory // Note: stderr is used instead // of "named.run" // if the server is started // with the '-f' option. severity dynamic; // log at the server's // current debug level }; channel default_stderr { stderr; // writes to stderr severity info; // only send priority info // and higher }; channel null { null; // toss anything sent to // this channel }; </pre> <p>The <span><strong class="command">default_debug</strong></span> channel has the special property that it only produces output when the server's debug level is nonzero. It normally writes to a file called <code class="filename">named.run</code> in the server's working directory.</p> <p>For security reasons, when the "<code class="option">-u</code>" command line option is used, the <code class="filename">named.run</code> file is created only after <span><strong class="command">named</strong></span> has changed to the new UID, and any debug output generated while <span><strong class="command">named</strong></span> is starting up and still running as root is discarded. If you need to capture this output, you must run the server with the "<code class="option">-g</code>" option and redirect standard error to a file.</p> <p>Once a channel is defined, it cannot be redefined. Thus you cannot alter the built-in channels directly, but you can modify the default logging by pointing categories at channels you have defined.</p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="the_category_phrase"></a>The <span><strong class="command">category</strong></span> Phrase</h4></div></div></div> <p>There are many categories, so you can send the logs you want to see wherever you want, without seeing logs you don't want. If you don't specify a list of channels for a category, then log messages in that category will be sent to the <span><strong class="command">default</strong></span> category instead. If you don't specify a default category, the following "default default" is used:</p> <pre class="programlisting">category default { default_syslog; default_debug; }; </pre> <p>As an example, let's say you want to log security events to a file, but you also want keep the default logging behavior. You'd specify the following:</p> <pre class="programlisting">channel my_security_channel { file "my_security_file"; severity info; }; category security { my_security_channel; default_syslog; default_debug; };</pre> <p>To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel:</p> <pre class="programlisting">category xfer-out { null; }; category notify { null; }; </pre> <p>Following are the available categories and brief descriptions of the types of log information they contain. More categories may be added in future <acronym class="acronym">BIND</acronym> releases.</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">default</strong></span></p></td> <td><p>The default category defines the logging options for those categories where no specific configuration has been defined.</p></td> </tr> <tr> <td><p><span><strong class="command">general</strong></span></p></td> <td><p>The catch-all. Many things still aren't classified into categories, and they all end up here.</p></td> </tr> <tr> <td><p><span><strong class="command">database</strong></span></p></td> <td><p>Messages relating to the databases used internally by the name server to store zone and cache data.</p></td> </tr> <tr> <td><p><span><strong class="command">security</strong></span></p></td> <td><p>Approval and denial of requests.</p></td> </tr> <tr> <td><p><span><strong class="command">config</strong></span></p></td> <td><p>Configuration file parsing and processing.</p></td> </tr> <tr> <td><p><span><strong class="command">resolver</strong></span></p></td> <td><p>DNS resolution, such as the recursive lookups performed on behalf of clients by a caching name server.</p></td> </tr> <tr> <td><p><span><strong class="command">xfer-in</strong></span></p></td> <td><p>Zone transfers the server is receiving.</p></td> </tr> <tr> <td><p><span><strong class="command">xfer-out</strong></span></p></td> <td><p>Zone transfers the server is sending.</p></td> </tr> <tr> <td><p><span><strong class="command">notify</strong></span></p></td> <td><p>The NOTIFY protocol.</p></td> </tr> <tr> <td><p><span><strong class="command">client</strong></span></p></td> <td><p>Processing of client requests.</p></td> </tr> <tr> <td><p><span><strong class="command">unmatched</strong></span></p></td> <td><p>Messages that named was unable to determine the class of or for which there was no matching <span><strong class="command">view</strong></span>. A one line summary is also logged to the <span><strong class="command">client</strong></span> category. This category is best sent to a file or stderr, by default it is sent to the <span><strong class="command">null</strong></span> channel.</p></td> </tr> <tr> <td><p><span><strong class="command">network</strong></span></p></td> <td><p>Network operations.</p></td> </tr> <tr> <td><p><span><strong class="command">update</strong></span></p></td> <td><p>Dynamic updates.</p></td> </tr> <tr> <td><p><span><strong class="command">update-security</strong></span></p></td> <td><p>Approval and denial of update requests.</p></td> </tr> <tr> <td><p><span><strong class="command">queries</strong></span></p></td> <td> <p>Specify where queries should be logged to.</p> <p> At startup, specifying the category <span><strong class="command">queries</strong></span> will also enable query logging unless <span><strong class="command">querylog</strong></span> option has been specified. </p> <p> The query log entry reports the client's IP address and port number, and the query name, class and type. It also reports whether the Recursion Desired flag was set (+ if set, - if not set), EDNS was in use (E) or if the query was signed (S).</p> <p><code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code> </p> <p><code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code> </p> </td> </tr> <tr> <td><p><span><strong class="command">dispatch</strong></span></p></td> <td><p>Dispatching of incoming packets to the server modules where they are to be processed. </p></td> </tr> <tr> <td><p><span><strong class="command">dnssec</strong></span></p></td> <td><p>DNSSEC and TSIG protocol processing. </p></td> </tr> <tr> <td><p><span><strong class="command">lame-servers</strong></span></p></td> <td><p>Lame servers. These are misconfigurations in remote servers, discovered by BIND 9 when trying to query those servers during resolution. </p></td> </tr> <tr> <td><p><span><strong class="command">delegation-only</strong></span></p></td> <td><p>Delegation only. Logs queries that have have been forced to NXDOMAIN as the result of a delegation-only zone or a <span><strong class="command">delegation-only</strong></span> in a hint or stub zone declaration. </p></td> </tr> </tbody> </table></div> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2578270"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div> <p> This is the grammar of the <span><strong class="command">lwres</strong></span> statement in the <code class="filename">named.conf</code> file:</p> <pre class="programlisting"><span><strong class="command">lwres</strong></span> { [<span class="optional"> listen-on { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>] [<span class="optional"> search { <em class="replaceable"><code>domain_name</code></em> ; [<span class="optional"> <em class="replaceable"><code>domain_name</code></em> ; ... </span>] }; </span>] [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2578343"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">lwres</strong></span> statement configures the name server to also act as a lightweight resolver server. (See <a href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called “Running a Resolver Daemon”</a>.) There may be be multiple <span><strong class="command">lwres</strong></span> statements configuring lightweight resolver servers with different properties.</p> <p>The <span><strong class="command">listen-on</strong></span> statement specifies a list of addresses (and ports) that this instance of a lightweight resolver daemon should accept requests on. If no port is specified, port 921 is used. If this statement is omitted, requests will be accepted on 127.0.0.1, port 921.</p> <p>The <span><strong class="command">view</strong></span> statement binds this instance of a lightweight resolver daemon to a view in the DNS namespace, so that the response will be constructed in the same manner as a normal DNS query matching this view. If this statement is omitted, the default view is used, and if there is no default view, an error is triggered.</p> <p>The <span><strong class="command">search</strong></span> statement is equivalent to the <span><strong class="command">search</strong></span> statement in <code class="filename">/etc/resolv.conf</code>. It provides a list of domains which are appended to relative names in queries.</p> <p>The <span><strong class="command">ndots</strong></span> statement is equivalent to the <span><strong class="command">ndots</strong></span> statement in <code class="filename">/etc/resolv.conf</code>. It indicates the minimum number of dots in a relative domain name that should result in an exact match lookup before search path elements are appended.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2578406"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting"> <span><strong class="command">masters</strong></span> <em class="replaceable"><code>name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] } ; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2578518"></a><span><strong class="command">masters</strong></span> Statement Definition and Usage </h3></div></div></div> <p><span><strong class="command">masters</strong></span> lists allow for a common set of masters to be easily used by multiple stub and slave zones.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2578533"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div> <p>This is the grammar of the <span><strong class="command">options</strong></span> statement in the <code class="filename">named.conf</code> file:</p> <pre class="programlisting">options { [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>] [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>] [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>] [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>] [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>] [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>] [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>] [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em>; </span>] [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> dnssec-lookaside <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em>; </span>] [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>] [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>] [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] | <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ; ... }; </span>] [<span class="optional"> check-names ( <em class="replaceable"><code>master</code></em> | <em class="replaceable"><code>slave</code></em> | <em class="replaceable"><code>response</code></em> )( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] [<span class="optional"> listen-on [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> listen-on-v6 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>] [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>] [<span class="optional"> query-source-v6 [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>] [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>] [<span class="optional"> transfers-in <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>] [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>] [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>] [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>] [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>] [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>]; [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>]; [<span class="optional"> rrset-order { <em class="replaceable"><code>order_spec</code></em> ; [<span class="optional"> <em class="replaceable"><code>order_spec</code></em> ; ... </span>] </span>] }; [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>] [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>] [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>] [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> preferred-glue ( <em class="replaceable"><code>A</code></em> | <em class="replaceable"><code>AAAA</code></em> | <em class="replaceable"><code>NONE</code></em> ); </span>] [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>] [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>] [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>; [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">options</strong></span> statement sets up global options to be used by <acronym class="acronym">BIND</acronym>. This statement may appear only once in a configuration file. If there is no <span><strong class="command">options</strong></span> statement, an options block with each option set to its default will be used.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">directory</strong></span></span></dt> <dd><p>The working directory of the server. Any non-absolute pathnames in the configuration file will be taken as relative to this directory. The default location for most server output files (e.g. <code class="filename">named.run</code>) is this directory. If a directory is not specified, the working directory defaults to `<code class="filename">.</code>', the directory from which the server was started. The directory specified should be an absolute path.</p></dd> <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt> <dd><p>When performing dynamic update of secure zones, the directory where the public and private key files should be found, if different than the current working directory. The directory specified must be an absolute path.</p></dd> <dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt> <dd><p><span class="emphasis"><em>This option is obsolete.</em></span> It was used in <acronym class="acronym">BIND</acronym> 8 to specify the pathname to the <span><strong class="command">named-xfer</strong></span> program. In <acronym class="acronym">BIND</acronym> 9, no separate <span><strong class="command">named-xfer</strong></span> program is needed; its functionality is built into the name server.</p></dd> <dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt> <dd><p>The domain appended to the names of all shared keys generated with <span><strong class="command">TKEY</strong></span>. When a client requests a <span><strong class="command">TKEY</strong></span> exchange, it may or may not specify the desired name for the key. If present, the name of the shared key will be "<code class="varname">client specified part</code>" + "<code class="varname">tkey-domain</code>". Otherwise, the name of the shared key will be "<code class="varname">random hex digits</code>" + "<code class="varname">tkey-domain</code>". In most cases, the <span><strong class="command">domainname</strong></span> should be the server's domain name.</p></dd> <dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt> <dd><p>The Diffie-Hellman key used by the server to generate shared keys with clients using the Diffie-Hellman mode of <span><strong class="command">TKEY</strong></span>. The server must be able to load the public and private keys from files in the working directory. In most cases, the keyname should be the server's host name.</p></dd> <dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt> <dd><p> This is for testing only. Do not use. </p></dd> <dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt> <dd><p>The pathname of the file the server dumps the database to when instructed to do so with <span><strong class="command">rndc dumpdb</strong></span>. If not specified, the default is <code class="filename">named_dump.db</code>.</p></dd> <dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt> <dd><p>The pathname of the file the server writes memory usage statistics to on exit. If not specified, the default is <code class="filename">named.memstats</code>.</p></dd> <dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt> <dd><p>The pathname of the file the server writes its process ID in. If not specified, the default is <code class="filename">/var/run/named.pid</code>. The pid-file is used by programs that want to send signals to the running name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the use of a PID file — no file will be written and any existing one will be removed. Note that <span><strong class="command">none</strong></span> is a keyword, not a file name, and therefore is not enclosed in double quotes.</p></dd> <dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt> <dd><p>The pathname of the file the server appends statistics to when instructed to do so using <span><strong class="command">rndc stats</strong></span>. If not specified, the default is <code class="filename">named.stats</code> in the server's current directory. The format of the file is described in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>.</p></dd> <dt><span class="term"><span><strong class="command">port</strong></span></span></dt> <dd><p> The UDP/TCP port number the server uses for receiving and sending DNS protocol traffic. The default is 53. This option is mainly intended for server testing; a server using a port other than 53 will not be able to communicate with the global DNS. </p></dd> <dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt> <dd><p> The source of entropy to be used by the server. Entropy is primarily needed for DNSSEC operations, such as TKEY transactions and dynamic update of signed zones. This options specifies the device (or file) from which to read entropy. If this is a file, operations requiring entropy will fail when the file has been exhausted. If not specified, the default value is <code class="filename">/dev/random</code> (or equivalent) when present, and none otherwise. The <span><strong class="command">random-device</strong></span> option takes effect during the initial configuration load at server startup time and is ignored on subsequent reloads.</p></dd> <dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt> <dd><p> If specified, the listed type (A or AAAA) will be emitted before other glue in the additional section of a query response. The default is not to prefer any type (NONE). </p></dd> <dt><span class="term"><span><strong class="command">root-delegation-only</strong></span></span></dt> <dd> <p> Turn on enforcement of delegation-only in TLDs (top level domains) and root zones with an optional exclude list. </p> <p> Note some TLDs are not delegation only (e.g. "DE", "LV", "US" and "MUSEUM"). </p> <pre class="programlisting"> options { root-delegation-only exclude { "de"; "lv"; "us"; "museum"; }; }; </pre> </dd> <dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt> <dd><p> Disable the specified DNSSEC algorithms at and below the specified name. Multiple <span><strong class="command">disable-algorithms</strong></span> statements are allowed. Only the most specific will be applied. </p></dd> <dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt> <dd><p> When set, <span><strong class="command">dnssec-lookaside</strong></span> provides the validator with an alternate method to validate DNSKEY records at the top of a zone. When a DNSKEY is at or below a domain specified by the deepest <span><strong class="command">dnssec-lookaside</strong></span>, and the normal dnssec validation has left the key untrusted, the trust-anchor will be append to the key name and a DLV record will be looked up to see if it can validate the key. If the DLV record validates a DNSKEY (similarly to the way a DS record does) the DNSKEY RRset is deemed to be trusted. </p></dd> <dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt> <dd><p> Specify heirarchies which must be or may not be secure (signed and validated). If <strong class="userinput"><code>yes</code></strong>, then named will only accept answers if they are secure. If <strong class="userinput"><code>no</code></strong>, then normal dnssec validation applies allowing for insecure answers to be accepted. The specified domain must be under a <span><strong class="command">trusted-key</strong></span> or <span><strong class="command">dnssec-lookaside</strong></span> must be active. </p></dd> </dl></div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="boolean_options"></a>Boolean Options</h4></div></div></div> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit is always set on NXDOMAIN responses, even if the server is not actually authoritative. The default is <strong class="userinput"><code>no</code></strong>; this is a change from <acronym class="acronym">BIND</acronym> 8. If you are using very old DNS software, you may need to set it to <strong class="userinput"><code>yes</code></strong>.</p></dd> <dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt> <dd><p>This option was used in <acronym class="acronym">BIND</acronym> 8 to enable checking for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs the checks.</p></dd> <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt> <dd> <p>If <strong class="userinput"><code>yes</code></strong>, then the server treats all zones as if they are doing zone transfers across a dial-on-demand dialup link, which can be brought up by traffic originating from this server. This has different effects according to zone type and concentrates the zone maintenance so that it all happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and hopefully during the one call. It also suppresses some of the normal zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.</p> <p>The <span><strong class="command">dialup</strong></span> option may also be specified in the <span><strong class="command">view</strong></span> and <span><strong class="command">zone</strong></span> statements, in which case it overrides the global <span><strong class="command">dialup</strong></span> option.</p> <p>If the zone is a master zone, then the server will send out a NOTIFY request to all the slaves (default). This should trigger the zone serial number check in the slave (providing it supports NOTIFY) allowing the slave to verify the zone while the connection is active. The set of servers to which NOTIFY is sent can be controlled by <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>.</p> <p>If the zone is a slave or stub zone, then the server will suppress the regular "zone up to date" (refresh) queries and only perform them when the <span><strong class="command">heartbeat-interval</strong></span> expires in addition to sending NOTIFY requests.</p> <p>Finer control can be achieved by using <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY messages, <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY messages and suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong> which suppresses normal refresh processing and sends refresh queries when the <span><strong class="command">heartbeat-interval</strong></span> expires, and <strong class="userinput"><code>passive</code></strong> which just disables normal refresh processing.</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> <col> <col> </colgroup> <tbody> <tr> <td><p>dialup mode</p></td> <td><p>normal refresh</p></td> <td><p>heart-beat refresh</p></td> <td><p>heart-beat notify</p></td> </tr> <tr> <td><p><span><strong class="command">no</strong></span> (default)</p></td> <td><p>yes</p></td> <td><p>no</p></td> <td><p>no</p></td> </tr> <tr> <td><p><span><strong class="command">yes</strong></span></p></td> <td><p>no</p></td> <td><p>yes</p></td> <td><p>yes</p></td> </tr> <tr> <td><p><span><strong class="command">notify</strong></span></p></td> <td><p>yes</p></td> <td><p>no</p></td> <td><p>yes</p></td> </tr> <tr> <td><p><span><strong class="command">refresh</strong></span></p></td> <td><p>no</p></td> <td><p>yes</p></td> <td><p>no</p></td> </tr> <tr> <td><p><span><strong class="command">passive</strong></span></p></td> <td><p>no</p></td> <td><p>no</p></td> <td><p>no</p></td> </tr> <tr> <td><p><span><strong class="command">notify-passive</strong></span></p></td> <td><p>no</p></td> <td><p>no</p></td> <td><p>yes</p></td> </tr> </tbody> </table></div> <p>Note that normal NOTIFY processing is not affected by <span><strong class="command">dialup</strong></span>.</p> </dd> <dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt> <dd><p>In <acronym class="acronym">BIND</acronym> 8, this option enabled simulating the obsolete DNS query type IQUERY. <acronym class="acronym">BIND</acronym> 9 never does IQUERY simulation. </p></dd> <dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt> <dd><p>This option is obsolete. In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong> caused the server to attempt to fetch glue resource records it didn't have when constructing the additional data section of a response. This is now considered a bad idea and BIND 9 never does it.</p></dd> <dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt> <dd><p>When the nameserver exits due receiving SIGTERM, flush or do not flush any pending zone writes. The default is <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>. </p></dd> <dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt> <dd><p>This option was incorrectly implemented in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9. To achieve the intended effect of <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong> and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead. </p></dd> <dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt> <dd><p>In BIND 8, this enables keeping of statistics for every host that the name server interacts with. Not implemented in BIND 9. </p></dd> <dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt> <dd><p><span class="emphasis"><em>This option is obsolete</em></span>. It was used in <acronym class="acronym">BIND</acronym> 8 to determine whether a transaction log was kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction log whenever possible. If you need to disable outgoing incremental zone transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>. </p></dd> <dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, then when generating responses the server will only add records to the authority and additional data sections when they are required (e.g. delegations, negative responses). This may improve the performance of the server. The default is <strong class="userinput"><code>no</code></strong>. </p></dd> <dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt> <dd><p>This option was used in <acronym class="acronym">BIND</acronym> 8 to allow a domain name to have multiple CNAME records in violation of the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 always strictly enforces the CNAME rules both in master files and dynamic updates. </p></dd> <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt> <dd> <p>If <strong class="userinput"><code>yes</code></strong> (the default), DNS NOTIFY messages are sent when a zone the server is authoritative for changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called “Notify”</a>. The messages are sent to the servers listed in the zone's NS records (except the master server identified in the SOA MNAME field), and to any servers listed in the <span><strong class="command">also-notify</strong></span> option. </p> <p> If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only to servers explicitly listed using <span><strong class="command">also-notify</strong></span>. If <strong class="userinput"><code>no</code></strong>, no notifies are sent. </p> <p> The <span><strong class="command">notify</strong></span> option may also be specified in the <span><strong class="command">zone</strong></span> statement, in which case it overrides the <span><strong class="command">options notify</strong></span> statement. It would only be necessary to turn off this option if it caused slaves to crash.</p> </dd> <dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, and a DNS query requests recursion, then the server will attempt to do all the work required to answer the query. If recursion is off and the server does not already know the answer, it will return a referral response. The default is <strong class="userinput"><code>yes</code></strong>. Note that setting <span><strong class="command">recursion no</strong></span> does not prevent clients from getting data from the server's cache; it only prevents new data from being cached as an effect of client queries. Caching may still occur as an effect the server's internal operation, such as NOTIFY address lookups. See also <span><strong class="command">fetch-glue</strong></span> above. </p></dd> <dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt> <dd> <p>Setting this to <strong class="userinput"><code>yes</code></strong> will cause the server to send NS records along with the SOA record for negative answers. The default is <strong class="userinput"><code>no</code></strong>.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>Not yet implemented in <acronym class="acronym">BIND</acronym> 9.</p> </div> </dd> <dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt> <dd><p><span class="emphasis"><em>This option is obsolete</em></span>. <acronym class="acronym">BIND</acronym> 9 always allocates query IDs from a pool. </p></dd> <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, the server will collect statistical data on all zones (unless specifically turned off on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span> in the <span><strong class="command">zone</strong></span> statement). These statistics may be accessed using <span><strong class="command">rndc stats</strong></span>, which will dump them to the file listed in the <span><strong class="command">statistics-file</strong></span>. See also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>. </p></dd> <dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt> <dd><p><span class="emphasis"><em>This option is obsolete</em></span>. If you need to disable IXFR to a particular server or servers see the information on the <span><strong class="command">provide-ixfr</strong></span> option in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and Usage”</a>. See also <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called “Incremental Zone Transfers (IXFR)”</a>. </p></dd> <dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt> <dd><p> See the description of <span><strong class="command">provide-ixfr</strong></span> in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and Usage”</a>. </p></dd> <dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt> <dd><p> See the description of <span><strong class="command">request-ixfr</strong></span> in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and Usage”</a>. </p></dd> <dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt> <dd><p>This option was used in <acronym class="acronym">BIND</acronym> 8 to make the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way as a space or tab character, to facilitate loading of zone files on a UNIX system that were generated on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>" and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines are always accepted, and the option is ignored.</p></dd> <dt> <span class="term"><span><strong class="command">additional-from-auth</strong></span>, </span><span class="term"><span><strong class="command">additional-from-cache</strong></span></span> </dt> <dd> <p> These options control the behavior of an authoritative server when answering queries which have additional data, or when following CNAME and DNAME chains. </p> <p> When both of these options are set to <strong class="userinput"><code>yes</code></strong> (the default) and a query is being answered from authoritative data (a zone configured into the server), the additional data section of the reply will be filled in using data from other authoritative zones and from the cache. In some situations this is undesirable, such as when there is concern over the correctness of the cache, or in servers where slave zones may be added and modified by untrusted third parties. Also, avoiding the search for this additional data will speed up server operations at the possible expense of additional queries to resolve what would otherwise be provided in the additional section. </p> <p> For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>, and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well, if known, even though they are not in the example.com zone. Setting these options to <span><strong class="command">no</strong></span> disables this behavior and makes the server only search for additional data in the zone it answers from. </p> <p> These options are intended for use in authoritative-only servers, or in authoritative-only views. Attempts to set them to <span><strong class="command">no</strong></span> without also specifying <span><strong class="command">recursion no</strong></span> will cause the server to ignore the options and log a warning message. </p> <p> Specifying <span><strong class="command">additional-from-cache no</strong></span> actually disables the use of the cache not only for additional data lookups but also when looking up the answer. This is usually the desired behavior in an authoritative-only server where the correctness of the cached data is an issue. </p> <p> When a name server is non-recursively queried for a name that is not below the apex of any served zone, it normally answers with an "upwards referral" to the root servers or the servers of some other known parent of the query name. Since the data in an upwards referral comes from the cache, the server will not be able to provide upwards referrals when <span><strong class="command">additional-from-cache no</strong></span> has been specified. Instead, it will respond to such queries with REFUSED. This should not cause any problems since upwards referrals are not required for the resolution process. </p> </dd> <dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, then an IPv4-mapped IPv6 address will match any address match list entries that match the corresponding IPv4 address. Enabling this option is sometimes useful on IPv6-enabled Linux systems, to work around a kernel quirk that causes IPv4 TCP connections such as zone transfers to be accepted on an IPv6 socket using mapped addresses, causing address match lists designed for IPv4 to fail to match. The use of this option for any other purpose is discouraged. </p></dd> <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt> <dd> <p> When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master zone from its zone file or receives a new version of a slave file by a non-incremental zone transfer, it will compare the new version to the previous one and calculate a set of differences. The differences are then logged in the zone's journal file such that the changes can be transmitted to downstream slaves as an incremental zone transfer. </p> <p> By allowing incremental zone transfers to be used for non-dynamic zones, this option saves bandwidth at the expense of increased CPU and memory consumption at the master. In particular, if the new version of a zone is completely different from the previous one, the set of differences will be of a size comparable to the combined size of the old and new zone version, and the server will need to temporarily allocate memory to hold this complete difference set. </p> </dd> <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt> <dd><p> This should be set when you have multiple masters for a zone and the addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, named will not log when the serial number on the master is less than what named currently has. The default is <strong class="userinput"><code>no</code></strong>. </p></dd> <dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt> <dd><p> Enable DNSSEC support in named. Unless set to <strong class="userinput"><code>yes</code></strong>, named behaves as if it does not support DNSSEC. The default is <strong class="userinput"><code>no</code></strong>. </p></dd> <dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt> <dd><p> Specify whether query logging should be started when named starts. If <span><strong class="command">querylog</strong></span> is not specified, then the query logging is determined by the presence of the logging category <span><strong class="command">queries</strong></span>. </p></dd> <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt> <dd> <p> This option is used to restrict the character set and syntax of certain domain names in master files and/or DNS responses received from the network. The default varies according to usage area. For <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>. For <span><strong class="command">slave</strong></span> zones the default is <span><strong class="command">warn</strong></span>. For answers received from the network (<span><strong class="command">response</strong></span>) the default is <span><strong class="command">ignore</strong></span>. </p> <p>The rules for legal hostnames and mail domains are derived from RFC 952 and RFC 821 as modified by RFC 1123. </p> <p><span><strong class="command">check-names</strong></span> applies to the owner names of A, AAA and MX records. It also applies to the domain names in the RDATA of NS, SOA and MX records. It also applies to the RDATA of PTR records where the owner name indicated that it is a reverse lookup of a hostname (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, IP6.INT). </p> </dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2581312"></a>Forwarding</h4></div></div></div> <p>The forwarding facility can be used to create a large site-wide cache on a few servers, reducing traffic over links to external name servers. It can also be used to allow queries by servers that do not have direct access to the Internet, but wish to look up exterior names anyway. Forwarding occurs only on those queries for which the server is not authoritative and does not have the answer in its cache.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt> <dd><p>This option is only meaningful if the forwarders list is not empty. A value of <code class="varname">first</code>, the default, causes the server to query the forwarders first — and if that doesn't answer the question, the server will then look for the answer itself. If <code class="varname">only</code> is specified, the server will only query the forwarders. </p></dd> <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt> <dd><p>Specifies the IP addresses to be used for forwarding. The default is the empty list (no forwarding). </p></dd> </dl></div> <p>Forwarding can also be configured on a per-domain basis, allowing for the global forwarding options to be overridden in a variety of ways. You can set particular domains to use different forwarders, or have a different <span><strong class="command">forward only/first</strong></span> behavior, or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone Statement Grammar">the section called “<span><strong class="command">zone</strong></span> Statement Grammar”</a>.</p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2581362"></a>Dual-stack Servers</h4></div></div></div> <p>Dual-stack servers are used as servers of last resort to work around problems in reachability due the lack of support for either IPv4 or IPv6 on the host machine.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt> <dd><p>Specifies host names or addresses of machines with access to both IPv4 and IPv6 transports. If a hostname is used, the server must be able to resolve the name using only the transport it has. If the machine is dual stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless access to a transport has been disabled on the command line (e.g. <span><strong class="command">named -4</strong></span>).</p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="access_control"></a>Access Control</h4></div></div></div> <p>Access to the server can be restricted based on the IP address of the requesting system. See <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a> for details on how to specify IP address lists.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt> <dd><p>Specifies which hosts are allowed to notify this server, a slave, of zone changes in addition to the zone masters. <span><strong class="command">allow-notify</strong></span> may also be specified in the <span><strong class="command">zone</strong></span> statement, in which case it overrides the <span><strong class="command">options allow-notify</strong></span> statement. It is only meaningful for a slave zone. If not specified, the default is to process notify messages only from a zone's master.</p></dd> <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt> <dd><p>Specifies which hosts are allowed to ask ordinary DNS questions. <span><strong class="command">allow-query</strong></span> may also be specified in the <span><strong class="command">zone</strong></span> statement, in which case it overrides the <span><strong class="command">options allow-query</strong></span> statement. If not specified, the default is to allow queries from all hosts.</p></dd> <dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt> <dd><p>Specifies which hosts are allowed to make recursive queries through this server. If not specified, the default is to allow recursive queries from all hosts. Note that disallowing recursive queries for a host does not prevent the host from retrieving data that is already in the server's cache. </p></dd> <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt> <dd> <p>Specifies which hosts are allowed to submit Dynamic DNS updates to slave zones to be forwarded to the master. The default is <strong class="userinput"><code>{ none; }</code></strong>, which means that no update forwarding will be performed. To enable update forwarding, specify <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>. Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or <strong class="userinput"><code>{ any; }</code></strong> is usually counterproductive, since the responsibility for update access control should rest with the master server, not the slaves.</p> <p>Note that enabling the update forwarding feature on a slave server may expose master servers relying on insecure IP address based access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for more details.</p> </dd> <dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt> <dd><p>This option was introduced for the smooth transition from AAAA to A6 and from "nibble labels" to binary labels. However, since both A6 and binary labels were then deprecated, this option was also deprecated. It is now ignored with some warning messages. </p></dd> <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt> <dd><p>Specifies which hosts are allowed to receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may also be specified in the <span><strong class="command">zone</strong></span> statement, in which case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement. If not specified, the default is to allow transfers to all hosts.</p></dd> <dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt> <dd><p>Specifies a list of addresses that the server will not accept queries from or use to resolve a query. Queries from these addresses will not be responded to. The default is <strong class="userinput"><code>none</code></strong>.</p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2581677"></a>Interfaces</h4></div></div></div> <p>The interfaces and ports that the server will answer queries from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes an optional port, and an <code class="varname">address_match_list</code>. The server will listen on all interfaces allowed by the address match list. If a port is not specified, port 53 will be used.</p> <p>Multiple <span><strong class="command">listen-on</strong></span> statements are allowed. For example,</p> <pre class="programlisting">listen-on { 5.6.7.8; }; listen-on port 1234 { !1.2.3.4; 1.2/16; }; </pre> <p>will enable the name server on port 53 for the IP address 5.6.7.8, and on port 1234 of an address on the machine in net 1.2 that is not 1.2.3.4.</p> <p>If no <span><strong class="command">listen-on</strong></span> is specified, the server will listen on port 53 on all interfaces.</p> <p>The <span><strong class="command">listen-on-v6</strong></span> option is used to specify the interfaces and the ports on which the server will listen for incoming queries sent using IPv6.</p> <p>When </p> <pre class="programlisting">{ any; }</pre> <p> is specified as the <code class="varname">address_match_list</code> for the <span><strong class="command">listen-on-v6</strong></span> option, the server does not bind a separate socket to each IPv6 interface address as it does for IPv4 if the operating system has enough API support for IPv6 (specifically if it conforms to RFC 3493 and RFC 3542). Instead, it listens on the IPv6 wildcard address. If the system only has incomplete API support for IPv6, however, the behavior is the same as that for IPv4.</p> <p>A list of particular IPv6 addresses can also be specified, in which case the server listens on a separate socket for each specified address, regardless of whether the desired API is supported by the system.</p> <p>Multiple <span><strong class="command">listen-on-v6</strong></span> options can be used. For example,</p> <pre class="programlisting">listen-on-v6 { any; }; listen-on-v6 port 1234 { !2001:db8::/32; any; }; </pre> <p>will enable the name server on port 53 for any IPv6 addresses (with a single wildcard socket), and on port 1234 of IPv6 addresses that is not in the prefix 2001:db8::/32 (with separate sockets for each matched address.)</p> <p>To make the server not listen on any IPv6 address, use</p> <pre class="programlisting">listen-on-v6 { none; }; </pre> <p>If no <span><strong class="command">listen-on-v6</strong></span> option is specified, the server will not listen on any IPv6 address.</p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2581834"></a>Query Address</h4></div></div></div> <p>If the server doesn't know the answer to a question, it will query other name servers. <span><strong class="command">query-source</strong></span> specifies the address and port used for such queries. For queries sent over IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option. If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted, a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>) will be used. If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted, a random unprivileged port will be used. The <span><strong class="command">avoid-v4-udp-ports</strong></span> and <span><strong class="command">avoid-v6-udp-ports</strong></span> options can be used to prevent named from selecting certain ports. The defaults are:</p> <pre class="programlisting">query-source address * port *; query-source-v6 address * port *; </pre> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>The address specified in the <span><strong class="command">query-source</strong></span> option is used for both UDP and TCP queries, but the port applies only to UDP queries. TCP queries always use a random unprivileged port.</p> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>See also <span><strong class="command">transfer-source</strong></span> and <span><strong class="command">notify-source</strong></span>.</p> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> Solaris 2.5.1 and earlier does not support setting the source address for TCP sockets. </p> </div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="zone_transfers"></a>Zone Transfers</h4></div></div></div> <p><acronym class="acronym">BIND</acronym> has mechanisms in place to facilitate zone transfers and set limits on the amount of load that transfers place on the system. The following options apply to zone transfers.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt> <dd><p>Defines a global list of IP addresses of name servers that are also sent NOTIFY messages whenever a fresh copy of the zone is loaded, in addition to the servers listed in the zone's NS records. This helps to ensure that copies of the zones will quickly converge on stealth servers. If an <span><strong class="command">also-notify</strong></span> list is given in a <span><strong class="command">zone</strong></span> statement, it will override the <span><strong class="command">options also-notify</strong></span> statement. When a <span><strong class="command">zone notify</strong></span> statement is set to <span><strong class="command">no</strong></span>, the IP addresses in the global <span><strong class="command">also-notify</strong></span> list will not be sent NOTIFY messages for that zone. The default is the empty list (no global notification list).</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt> <dd><p>Inbound zone transfers running longer than this many minutes will be terminated. The default is 120 minutes (2 hours). The maximum value is 28 days (40320 minutes).</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt> <dd><p>Inbound zone transfers making no progress in this many minutes will be terminated. The default is 60 minutes (1 hour). The maximum value is 28 days (40320 minutes).</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt> <dd><p>Outbound zone transfers running longer than this many minutes will be terminated. The default is 120 minutes (2 hours). The maximum value is 28 days (40320 minutes).</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt> <dd><p>Outbound zone transfers making no progress in this many minutes will be terminated. The default is 60 minutes (1 hour). The maximum value is 28 days (40320 minutes).</p></dd> <dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt> <dd><p>Slave servers will periodically query master servers to find out if zone serial numbers have changed. Each such query uses a minute amount of the slave server's network bandwidth. To limit the amount of bandwidth used, BIND 9 limits the rate at which queries are sent. The value of the <span><strong class="command">serial-query-rate</strong></span> option, an integer, is the maximum number of queries sent per second. The default is 20. </p></dd> <dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt> <dd><p>In BIND 8, the <span><strong class="command">serial-queries</strong></span> option set the maximum number of concurrent serial number queries allowed to be outstanding at any given time. BIND 9 does not limit the number of outstanding serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option. Instead, it limits the rate at which the queries are sent as defined using the <span><strong class="command">serial-query-rate</strong></span> option. </p></dd> <dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt> <dd><p> Zone transfers can be sent using two different formats, <span><strong class="command">one-answer</strong></span> and <span><strong class="command">many-answers</strong></span>. The <span><strong class="command">transfer-format</strong></span> option is used on the master server to determine which format it sends. <span><strong class="command">one-answer</strong></span> uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is more efficient, but is only supported by relatively new slave servers, such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym> 8.x and patched versions of <acronym class="acronym">BIND</acronym> 4.9.5. The <span><strong class="command">many-answers</strong></span> format is also supported by recent Microsoft Windows nameservers. The default is <span><strong class="command">many-answers</strong></span>. <span><strong class="command">transfer-format</strong></span> may be overridden on a per-server basis by using the <span><strong class="command">server</strong></span> statement. </p></dd> <dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt> <dd><p>The maximum number of inbound zone transfers that can be running concurrently. The default value is <code class="literal">10</code>. Increasing <span><strong class="command">transfers-in</strong></span> may speed up the convergence of slave zones, but it also may increase the load on the local system.</p></dd> <dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt> <dd><p>The maximum number of outbound zone transfers that can be running concurrently. Zone transfer requests in excess of the limit will be refused. The default value is <code class="literal">10</code>.</p></dd> <dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt> <dd><p>The maximum number of inbound zone transfers that can be concurrently transferring from a given remote name server. The default value is <code class="literal">2</code>. Increasing <span><strong class="command">transfers-per-ns</strong></span> may speed up the convergence of slave zones, but it also may increase the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase of the <span><strong class="command">server</strong></span> statement.</p></dd> <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt> <dd><p><span><strong class="command">transfer-source</strong></span> determines which local address will be bound to IPv4 TCP connections used to fetch zones transferred inbound by the server. It also determines the source IPv4 address, and optionally the UDP port, used for the refresh queries and forwarded dynamic updates. If not set, it defaults to a system controlled value which will usually be the address of the interface "closest to" the remote end. This address must appear in the remote end's <span><strong class="command">allow-transfer</strong></span> option for the zone being transferred, if one is specified. This statement sets the <span><strong class="command">transfer-source</strong></span> for all zones, but can be overridden on a per-view or per-zone basis by including a <span><strong class="command">transfer-source</strong></span> statement within the <span><strong class="command">view</strong></span> or <span><strong class="command">zone</strong></span> block in the configuration file.</p></dd> <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt> <dd><p>The same as <span><strong class="command">transfer-source</strong></span>, except zone transfers are performed using IPv6.</p></dd> <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt> <dd> <p> An alternate transfer source if the one listed in <span><strong class="command">transfer-source</strong></span> fails and <span><strong class="command">use-alt-transfer-source</strong></span> is set. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> If you do not wish the alternate transfer source to be used, you should set <span><strong class="command">use-alt-transfer-source</strong></span> appropriately and you should not depend upon getting a answer back to the first refresh query. </div> </dd> <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt> <dd><p>An alternate transfer source if the one listed in <span><strong class="command">transfer-source-v6</strong></span> fails and <span><strong class="command">use-alt-transfer-source</strong></span> is set.</p></dd> <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt> <dd><p>Use the alternate transfer sources or not. If views are specified this defaults to <span><strong class="command">no</strong></span> otherwise it defaults to <span><strong class="command">yes</strong></span> (for BIND 8 compatibility).</p></dd> <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt> <dd> <p><span><strong class="command">notify-source</strong></span> determines which local source address, and optionally UDP port, will be used to send NOTIFY messages. This address must appear in the slave server's <span><strong class="command">masters</strong></span> zone clause or in an <span><strong class="command">allow-notify</strong></span> clause. This statement sets the <span><strong class="command">notify-source</strong></span> for all zones, but can be overridden on a per-zone or per-view basis by including a <span><strong class="command">notify-source</strong></span> statement within the <span><strong class="command">zone</strong></span> or <span><strong class="command">view</strong></span> block in the configuration file.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> Solaris 2.5.1 and earlier does not support setting the source address for TCP sockets. </p> </div> </dd> <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt> <dd><p>Like <span><strong class="command">notify-source</strong></span>, but applies to notify messages sent to IPv6 addresses.</p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2582444"></a>Bad UDP Port Lists</h4></div></div></div> <p> <span><strong class="command">avoid-v4-udp-ports</strong></span> and <span><strong class="command">avoid-v6-udp-ports</strong></span> specify a list of IPv4 and IPv6 UDP ports that will not be used as system assigned source ports for UDP sockets. These lists prevent named from choosing as its random source port a port that is blocked by your firewall. If a query went out with such a source port, the answer would not get by the firewall and the name server would have to query again. </p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2570036"></a>Operating System Resource Limits</h4></div></div></div> <p>The server's usage of many system resources can be limited. Scaled values are allowed when specifying resource limits. For example, <span><strong class="command">1G</strong></span> can be used instead of <span><strong class="command">1073741824</strong></span> to specify a limit of one gigabyte. <span><strong class="command">unlimited</strong></span> requests unlimited use, or the maximum available amount. <span><strong class="command">default</strong></span> uses the limit that was in force when the server was started. See the description of <span><strong class="command">size_spec</strong></span> in <a href="Bv9ARM.ch06.html#configuration_file_elements" title="Configuration File Elements">the section called “Configuration File Elements”</a>.</p> <p>The following options set operating system resource limits for the name server process. Some operating systems don't support some or any of the limits. On such systems, a warning will be issued if the unsupported limit is used.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt> <dd><p>The maximum size of a core dump. The default is <code class="literal">default</code>.</p></dd> <dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt> <dd><p>The maximum amount of data memory the server may use. The default is <code class="literal">default</code>. This is a hard limit on server memory usage. If the server attempts to allocate memory in excess of this limit, the allocation will fail, which may in turn leave the server unable to perform DNS service. Therefore, this option is rarely useful as a way of limiting the amount of memory used by the server, but it can be used to raise an operating system data size limit that is too small by default. If you wish to limit the amount of memory used by the server, use the <span><strong class="command">max-cache-size</strong></span> and <span><strong class="command">recursive-clients</strong></span> options instead. </p></dd> <dt><span class="term"><span><strong class="command">files</strong></span></span></dt> <dd><p>The maximum number of files the server may have open concurrently. The default is <code class="literal">unlimited</code>. </p></dd> <dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt> <dd><p>The maximum amount of stack memory the server may use. The default is <code class="literal">default</code>.</p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2570205"></a>Server Resource Limits</h4></div></div></div> <p>The following options set limits on the server's resource consumption that are enforced internally by the server rather than the operating system.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt> <dd><p>This option is obsolete; it is accepted and ignored for BIND 8 compatibility. The option <span><strong class="command">max-journal-size</strong></span> performs a similar function in BIND 8. </p></dd> <dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt> <dd><p>Sets a maximum size for each journal file (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called “The journal file”</a>). When the journal file approaches the specified size, some of the oldest transactions in the journal will be automatically removed. The default is <code class="literal">unlimited</code>.</p></dd> <dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt> <dd><p>In BIND 8, specifies the maximum number of host statistics entries to be kept. Not implemented in BIND 9. </p></dd> <dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt> <dd><p>The maximum number of simultaneous recursive lookups the server will perform on behalf of clients. The default is <code class="literal">1000</code>. Because each recursing client uses a fair bit of memory, on the order of 20 kilobytes, the value of the <span><strong class="command">recursive-clients</strong></span> option may have to be decreased on hosts with limited memory. </p></dd> <dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt> <dd><p>The maximum number of simultaneous client TCP connections that the server will accept. The default is <code class="literal">100</code>.</p></dd> <dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt> <dd><p>The maximum amount of memory to use for the server's cache, in bytes. When the amount of data in the cache reaches this limit, the server will cause records to expire prematurely so that the limit is not exceeded. In a server with multiple views, the limit applies separately to the cache of each view. The default is <code class="literal">unlimited</code>, meaning that records are purged from the cache only when their TTLs expire. </p></dd> <dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt> <dd><p>The listen queue depth. The default and minimum is 3. If the kernel supports the accept filter "dataready" this also controls how many TCP connections that will be queued in kernel space waiting for some data before being passed to accept. Values less than 3 will be silently raised. </p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2584723"></a>Periodic Task Intervals</h4></div></div></div> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt> <dd><p>The server will remove expired resource records from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes. The default is 60 minutes. The maximum value is 28 days (40320 minutes). If set to 0, no periodic cleaning will occur.</p></dd> <dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt> <dd><p>The server will perform zone maintenance tasks for all zones marked as <span><strong class="command">dialup</strong></span> whenever this interval expires. The default is 60 minutes. Reasonable values are up to 1 day (1440 minutes). The maximum value is 28 days (40320 minutes). If set to 0, no zone maintenance for these zones will occur.</p></dd> <dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt> <dd><p>The server will scan the network interface list every <span><strong class="command">interface-interval</strong></span> minutes. The default is 60 minutes. The maximum value is 28 days (40320 minutes). If set to 0, interface scanning will only occur when the configuration file is loaded. After the scan, the server will begin listening for queries on any newly discovered interfaces (provided they are allowed by the <span><strong class="command">listen-on</strong></span> configuration), and will stop listening on interfaces that have gone away.</p></dd> <dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt> <dd> <p>Name server statistics will be logged every <span><strong class="command">statistics-interval</strong></span> minutes. The default is 60. The maximum value is 28 days (40320 minutes). If set to 0, no statistics will be logged.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>Not yet implemented in <acronym class="acronym">BIND</acronym>9.</p> </div> </dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="topology"></a>Topology</h4></div></div></div> <p>All other things being equal, when the server chooses a name server to query from a list of name servers, it prefers the one that is topologically closest to itself. The <span><strong class="command">topology</strong></span> statement takes an <span><strong class="command">address_match_list</strong></span> and interprets it in a special way. Each top-level list element is assigned a distance. Non-negated elements get a distance based on their position in the list, where the closer the match is to the start of the list, the shorter the distance is between it and the server. A negated match will be assigned the maximum distance from the server. If there is no match, the address will get a distance which is further than any non-negated list element, and closer than any negated element. For example,</p> <pre class="programlisting">topology { 10/8; !1.2.3/24; { 1.2/16; 3/8; }; };</pre> <p>will prefer servers on network 10 the most, followed by hosts on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the exception of hosts on network 1.2.3 (netmask 255.255.255.0), which is preferred least of all.</p> <p>The default topology is</p> <pre class="programlisting"> topology { localhost; localnets; }; </pre> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>The <span><strong class="command">topology</strong></span> option is not implemented in <acronym class="acronym">BIND</acronym> 9. </p> </div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div> <p>The response to a DNS query may consist of multiple resource records (RRs) forming a resource records set (RRset). The name server will normally return the RRs within the RRset in an indeterminate order (but see the <span><strong class="command">rrset-order</strong></span> statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>). The client resolver code should rearrange the RRs as appropriate, that is, using any addresses on the local net in preference to other addresses. However, not all resolvers can do this or are correctly configured. When a client is using a local server, the sorting can be performed in the server, based on the client's address. This only requires configuring the name servers, not all the clients.</p> <p>The <span><strong class="command">sortlist</strong></span> statement (see below) takes an <span><strong class="command">address_match_list</strong></span> and interprets it even more specifically than the <span><strong class="command">topology</strong></span> statement does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called “Topology”</a>). Each top level statement in the <span><strong class="command">sortlist</strong></span> must itself be an explicit <span><strong class="command">address_match_list</strong></span> with one or two elements. The first element (which may be an IP address, an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>) of each top level list is checked against the source address of the query until a match is found.</p> <p>Once the source address of the query has been matched, if the top level statement contains only one element, the actual primitive element that matched the source address is used to select the address in the response to move to the beginning of the response. If the statement is a list of two elements, then the second element is treated the same as the <span><strong class="command">address_match_list</strong></span> in a <span><strong class="command">topology</strong></span> statement. Each top level element is assigned a distance and the address in the response with the minimum distance is moved to the beginning of the response.</p> <p>In the following example, any queries received from any of the addresses of the host itself will get responses preferring addresses on any of the locally connected networks. Next most preferred are addresses on the 192.168.1/24 network, and after that either the 192.168.2/24 or 192.168.3/24 network with no preference shown between these two networks. Queries received from a host on the 192.168.1/24 network will prefer other addresses on that network to the 192.168.2/24 and 192.168.3/24 networks. Queries received from a host on the 192.168.4/24 or the 192.168.5/24 network will only prefer other addresses on their directly connected networks.</p> <pre class="programlisting">sortlist { { localhost; // IF the local host { localnets; // THEN first fit on the 192.168.1/24; // following nets { 192.168.2/24; 192.168.3/24; }; }; }; { 192.168.1/24; // IF on class C 192.168.1 { 192.168.1/24; // THEN use .1, or .2 or .3 { 192.168.2/24; 192.168.3/24; }; }; }; { 192.168.2/24; // IF on class C 192.168.2 { 192.168.2/24; // THEN use .2, or .1 or .3 { 192.168.1/24; 192.168.3/24; }; }; }; { 192.168.3/24; // IF on class C 192.168.3 { 192.168.3/24; // THEN use .3, or .1 or .2 { 192.168.1/24; 192.168.2/24; }; }; }; { { 192.168.4/24; 192.168.5/24; }; // if .4 or .5, prefer that net }; };</pre> <p>The following example will give reasonable behavior for the local host and hosts on directly connected networks. It is similar to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent to queries from the local host will favor any of the directly connected networks. Responses sent to queries from any other hosts on a directly connected network will prefer addresses on that same network. Responses to other queries will not be sorted.</p> <pre class="programlisting">sortlist { { localhost; localnets; }; { localnets; }; }; </pre> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div> <p>When multiple records are returned in an answer it may be useful to configure the order of the records placed into the response. The <span><strong class="command">rrset-order</strong></span> statement permits configuration of the ordering of the records in a multiple record response. See also the <span><strong class="command">sortlist</strong></span> statement, <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a>. </p> <p>An <span><strong class="command">order_spec</strong></span> is defined as follows:</p> <pre class="programlisting">[<span class="optional"> class <em class="replaceable"><code>class_name</code></em> </span>][<span class="optional"> type <em class="replaceable"><code>type_name</code></em> </span>][<span class="optional"> name <em class="replaceable"><code>"domain_name"</code></em></span>] order <em class="replaceable"><code>ordering</code></em> </pre> <p>If no class is specified, the default is <span><strong class="command">ANY</strong></span>. If no type is specified, the default is <span><strong class="command">ANY</strong></span>. If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk).</p> <p>The legal values for <span><strong class="command">ordering</strong></span> are:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">fixed</strong></span></p></td> <td><p>Records are returned in the order they are defined in the zone file.</p></td> </tr> <tr> <td><p><span><strong class="command">random</strong></span></p></td> <td><p>Records are returned in some random order.</p></td> </tr> <tr> <td><p><span><strong class="command">cyclic</strong></span></p></td> <td><p>Records are returned in a round-robin order.</p></td> </tr> </tbody> </table></div> <p>For example:</p> <pre class="programlisting">rrset-order { class IN type A name "host.example.com" order random; order cyclic; }; </pre> <p>will cause any responses for type A records in class IN that have "<code class="literal">host.example.com</code>" as a suffix, to always be returned in random order. All other records are returned in cyclic order.</p> <p>If multiple <span><strong class="command">rrset-order</strong></span> statements appear, they are not combined — the last one applies.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>The <span><strong class="command">rrset-order</strong></span> statement is not yet fully implemented in <acronym class="acronym">BIND</acronym> 9. BIND 9 currently does not support "fixed" ordering. </p> </div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="tuning"></a>Tuning</h4></div></div></div> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt> <dd><p>Sets the number of seconds to cache a lame server indication. 0 disables caching. (This is <span class="bold"><strong>NOT</strong></span> recommended.) The default is <code class="literal">600</code> (10 minutes) and the maximum value is <code class="literal">1800</code> (30 minutes).</p></dd> <dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt> <dd><p>To reduce network traffic and increase performance, the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is used to set a maximum retention time for these answers in the server in seconds. The default <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours). <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed 7 days and will be silently truncated to 7 days if set to a greater value.</p></dd> <dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt> <dd><p>Sets the maximum time for which the server will cache ordinary (positive) answers. The default is one week (7 days).</p></dd> <dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt> <dd> <p>The minimum number of root servers that is required for a request for the root servers to be accepted. The default is <strong class="userinput"><code>2</code></strong>.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>Not implemented in <acronym class="acronym">BIND</acronym> 9.</p> </div> </dd> <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt> <dd><p>Specifies the number of days into the future when DNSSEC signatures automatically generated as a result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called “Dynamic Update”</a>) will expire. The default is <code class="literal">30</code> days. The maximum value is 10 years (3660 days). The signature inception time is unconditionally set to one hour before the current time to allow for a limited amount of clock skew.</p></dd> <dt> <span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span> </dt> <dd> <p> These options control the server's behavior on refreshing a zone (querying for SOA changes) or retrying failed transfers. Usually the SOA values for the zone are used, but these values are set by the master, giving slave server administrators little control over their contents. </p> <p> These options allow the administrator to set a minimum and maximum refresh and retry time either per-zone, per-view, or globally. These options are valid for slave and stub zones, and clamp the SOA refresh and retry times to the specified values. </p> </dd> <dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt> <dd><p> <span><strong class="command">edns-udp-size</strong></span> sets the advertised EDNS UDP buffer size in bytes. Valid values are 512 to 4096 bytes (values outside this range will be silently adjusted). The default value is 4096. The usual reason for setting edns-udp-size to a non-default value it to get UDP answers to pass through broken firewalls that block fragmented packets and/or block UDP packets that are greater than 512 bytes. </p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="builtin"></a>Built-in server information zones</h4></div></div></div> <p>The server provides some helpful diagnostic information through a number of built-in zones under the pseudo-top-level-domain <code class="literal">bind</code> in the <span><strong class="command">CHAOS</strong></span> class. These zones are part of a built-in view (see <a href="Bv9ARM.ch06.html#view_statement_grammar" title="view Statement Grammar">the section called “<span><strong class="command">view</strong></span> Statement Grammar”</a>) of class <span><strong class="command">CHAOS</strong></span> which is separate from the default view of class <span><strong class="command">IN</strong></span>; therefore, any global server options such as <span><strong class="command">allow-query</strong></span> do not apply the these zones. If you feel the need to disable these zones, use the options below, or hide the built-in <span><strong class="command">CHAOS</strong></span> view by defining an explicit view of class <span><strong class="command">CHAOS</strong></span> that matches all clients.</p> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">version</strong></span></span></dt> <dd><p>The version the server should report via a query of the name <code class="literal">version.bind</code> with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. The default is the real version number of this server. Specifying <span><strong class="command">version none</strong></span> disables processing of the queries.</p></dd> <dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt> <dd><p>The hostname the server should report via a query of the name <code class="filename">hostname.bind</code> with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. This defaults to the hostname of the machine hosting the name server as found by the gethostname() function. The primary purpose of such queries is to identify which of a group of anycast servers is actually answering your queries. Specifying <span><strong class="command">hostname none;</strong></span> disables processing of the queries.</p></dd> <dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt> <dd><p>The ID of the server should report via a query of the name <code class="filename">ID.SERVER</code> with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. The primary purpose of such queries is to identify which of a group of anycast servers is actually answering your queries. Specifying <span><strong class="command">server-id none;</strong></span> disables processing of the queries. Specifying <span><strong class="command">server-id hostname;</strong></span> will cause named to use the hostname as found by the gethostname() function. The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>. </p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="statsfile"></a>The Statistics File</h4></div></div></div> <p>The statistics file generated by <acronym class="acronym">BIND</acronym> 9 is similar, but not identical, to that generated by <acronym class="acronym">BIND</acronym> 8. </p> <p>The statistics dump begins with a line, like:</p> <p> <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span> </p> <p>The numberr in parentheses is a standard Unix-style timestamp, measured as seconds since January 1, 1970. Following that line are a series of lines containing a counter type, the value of the counter, optionally a zone name, and optionally a view name. The lines without view and zone listed are global statistics for the entire server. Lines with a zone and view name for the given view and zone (the view name is omitted for the default view). </p> <p> The statistics dump ends with the line where the number is identical to the number in the beginning line; for example: </p> <p> <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span> </p> <p>The following statistics counters are maintained:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">success</strong></span></p></td> <td><p>The number of successful queries made to the server or zone. A successful query is defined as query which returns a NOERROR response with at least one answer RR.</p></td> </tr> <tr> <td><p><span><strong class="command">referral</strong></span></p></td> <td><p>The number of queries which resulted in referral responses.</p></td> </tr> <tr> <td><p><span><strong class="command">nxrrset</strong></span></p></td> <td><p>The number of queries which resulted in NOERROR responses with no data.</p></td> </tr> <tr> <td><p><span><strong class="command">nxdomain</strong></span></p></td> <td><p>The number of queries which resulted in NXDOMAIN responses.</p></td> </tr> <tr> <td><p><span><strong class="command">failure</strong></span></p></td> <td><p>The number of queries which resulted in a failure response other than those above.</p></td> </tr> <tr> <td><p><span><strong class="command">recursion</strong></span></p></td> <td><p>The number of queries which caused the server to perform recursion in order to find the final answer.</p></td> </tr> </tbody> </table></div> <p> Each query received by the server will cause exactly one of <span><strong class="command">success</strong></span>, <span><strong class="command">referral</strong></span>, <span><strong class="command">nxrrset</strong></span>, <span><strong class="command">nxdomain</strong></span>, or <span><strong class="command">failure</strong></span> to be incremented, and may additionally cause the <span><strong class="command">recursion</strong></span> counter to be incremented. </p> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">server <em class="replaceable"><code>ip_addr</code></em> { [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>] [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>] [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">server</strong></span> statement defines characteristics to be associated with a remote name server.</p> <p> The <span><strong class="command">server</strong></span> statement can occur at the top level of the configuration file or inside a <span><strong class="command">view</strong></span> statement. If a <span><strong class="command">view</strong></span> statement contains one or more <span><strong class="command">server</strong></span> statements, only those apply to the view and any top-level ones are ignored. If a view contains no <span><strong class="command">server</strong></span> statements, any top-level <span><strong class="command">server</strong></span> statements are used as defaults. </p> <p>If you discover that a remote server is giving out bad data, marking it as bogus will prevent further queries to it. The default value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>.</p> <p>The <span><strong class="command">provide-ixfr</strong></span> clause determines whether the local server, acting as master, will respond with an incremental zone transfer when the given remote server, a slave, requests it. If set to <span><strong class="command">yes</strong></span>, incremental transfer will be provided whenever possible. If set to <span><strong class="command">no</strong></span>, all transfers to the remote server will be non-incremental. If not set, the value of the <span><strong class="command">provide-ixfr</strong></span> option in the view or global options block is used as a default.</p> <p>The <span><strong class="command">request-ixfr</strong></span> clause determines whether the local server, acting as a slave, will request incremental zone transfers from the given remote server, a master. If not set, the value of the <span><strong class="command">request-ixfr</strong></span> option in the view or global options block is used as a default.</p> <p>IXFR requests to servers that do not support IXFR will automatically fall back to AXFR. Therefore, there is no need to manually list which servers support IXFR and which ones do not; the global default of <span><strong class="command">yes</strong></span> should always work. The purpose of the <span><strong class="command">provide-ixfr</strong></span> and <span><strong class="command">request-ixfr</strong></span> clauses is to make it possible to disable the use of IXFR even when both master and slave claim to support it, for example if one of the servers is buggy and crashes or corrupts data when IXFR is used.</p> <p>The <span><strong class="command">edns</strong></span> clause determines whether the local server will attempt to use EDNS when communicating with the remote server. The default is <span><strong class="command">yes</strong></span>.</p> <p>The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>, uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym> 8.x, and patched versions of <acronym class="acronym">BIND</acronym> 4.9.5. You can specify which method to use for a server with the <span><strong class="command">transfer-format</strong></span> option. If <span><strong class="command">transfer-format</strong></span> is not specified, the <span><strong class="command">transfer-format</strong></span> specified by the <span><strong class="command">options</strong></span> statement will be used.</p> <p><span><strong class="command">transfers</strong></span> is used to limit the number of concurrent inbound zone transfers from the specified server. If no <span><strong class="command">transfers</strong></span> clause is specified, the limit is set according to the <span><strong class="command">transfers-per-ns</strong></span> option.</p> <p>The <span><strong class="command">keys</strong></span> clause identifies a <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement, to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>) when talking to the remote server. When a request is sent to the remote server, a request signature will be generated using the key specified here and appended to the message. A request originating from the remote server is not required to be signed by this key.</p> <p>Although the grammar of the <span><strong class="command">keys</strong></span> clause allows for multiple keys, only a single key per server is currently supported.</p> <p>The <span><strong class="command">transfer-source</strong></span> and <span><strong class="command">transfer-source-v6</strong></span> clauses specify the IPv4 and IPv6 source address to be used for zone transfer with the remote server, respectively. For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can be specified. Similarly, for an IPv6 remote server, only <span><strong class="command">transfer-source-v6</strong></span> can be specified. For more details, see the description of <span><strong class="command">transfer-source</strong></span> and <span><strong class="command">transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2586290"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">trusted-keys { <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; [<span class="optional"> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; [<span class="optional">...</span>]</span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2586338"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition and Usage</h3></div></div></div> <p> The <span><strong class="command">trusted-keys</strong></span> statement defines DNSSEC security roots. DNSSEC is described in <a href="Bv9ARM.ch04.html#DNSSEC" title="DNSSEC">the section called “DNSSEC”</a>. A security root is defined when the public key for a non-authoritative zone is known, but cannot be securely obtained through DNS, either because it is the DNS root zone or because its parent zone is unsigned. Once a key has been configured as a trusted key, it is treated as if it had been validated and proven secure. The resolver attempts DNSSEC validation on all DNS data in subdomains of a security root. </p> <p> All keys (and corresponding zones) listed in <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless of what parent zones say. Similarly for all keys listed in <span><strong class="command">trusted-keys</strong></span> only those keys are used to validate the DNSKEY RRset. The parent's DS RRset will not be used. </p> <p> The <span><strong class="command">trusted-keys</strong></span> statement can contain multiple key entries, each consisting of the key's domain name, flags, protocol, algorithm, and the Base-64 representation of the key data. </p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">view <em class="replaceable"><code>view_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { match-clients { <em class="replaceable"><code>address_match_list</code></em> } ; match-destinations { <em class="replaceable"><code>address_match_list</code></em> } ; match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ; [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>] [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>] }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2586420"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div> <p>The <span><strong class="command">view</strong></span> statement is a powerful new feature of <acronym class="acronym">BIND</acronym> 9 that lets a name server answer a DNS query differently depending on who is asking. It is particularly useful for implementing split DNS setups without having to run multiple servers.</p> <p>Each <span><strong class="command">view</strong></span> statement defines a view of the DNS namespace that will be seen by a subset of clients. A client matches a view if its source IP address matches the <code class="varname">address_match_list</code> of the view's <span><strong class="command">match-clients</strong></span> clause and its destination IP address matches the <code class="varname">address_match_list</code> of the view's <span><strong class="command">match-destinations</strong></span> clause. If not specified, both <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span> default to matching all addresses. In addition to checking IP addresses <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span> can also take <span><strong class="command">keys</strong></span> which provide an mechanism for the client to select the view. A view can also be specified as <span><strong class="command">match-recursive-only</strong></span>, which means that only recursive requests from matching clients will match that view. The order of the <span><strong class="command">view</strong></span> statements is significant — a client request will be resolved in the context of the first <span><strong class="command">view</strong></span> that it matches.</p> <p>Zones defined within a <span><strong class="command">view</strong></span> statement will be only be accessible to clients that match the <span><strong class="command">view</strong></span>. By defining a zone of the same name in multiple views, different zone data can be given to different clients, for example, "internal" and "external" clients in a split DNS setup.</p> <p>Many of the options given in the <span><strong class="command">options</strong></span> statement can also be used within a <span><strong class="command">view</strong></span> statement, and then apply only when resolving queries with that view. When no view-specific value is given, the value in the <span><strong class="command">options</strong></span> statement is used as a default. Also, zone options can have default values specified in the <span><strong class="command">view</strong></span> statement; these view-specific defaults take precedence over those in the <span><strong class="command">options</strong></span> statement.</p> <p>Views are class specific. If no class is given, class IN is assumed. Note that all non-IN views must contain a hint zone, since only the IN class has compiled-in default hints.</p> <p>If there are no <span><strong class="command">view</strong></span> statements in the config file, a default view that matches any client is automatically created in class IN. Any <span><strong class="command">zone</strong></span> statements specified on the top level of the configuration file are considered to be part of this default view, and the <span><strong class="command">options</strong></span> statement will apply to the default view. If any explicit <span><strong class="command">view</strong></span> statements are present, all <span><strong class="command">zone</strong></span> statements must occur inside <span><strong class="command">view</strong></span> statements.</p> <p>Here is an example of a typical split DNS setup implemented using <span><strong class="command">view</strong></span> statements:</p> <pre class="programlisting">view "internal" { // This should match our internal networks. match-clients { 10.0.0.0/8; }; // Provide recursive service to internal clients only. recursion yes; // Provide a complete view of the example.com zone // including addresses of internal hosts. zone "example.com" { type master; file "example-internal.db"; }; }; view "external" { // Match all clients not matched by the previous view. match-clients { any; }; // Refuse recursive service to external clients. recursion no; // Provide a restricted view of the example.com zone // containing only publicly accessible hosts. zone "example.com" { type master; file "example-external.db"; }; }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span> Statement Grammar</h3></div></div></div> <pre class="programlisting">zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type master; [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> update-policy { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] } ; </span>] [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> ; </span>] [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>] }; zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type slave; [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] } ; </span>] [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> ; </span>] [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>] }; zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type hint; [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; // Not Implemented. </span>] }; zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type stub; [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> } ; </span>] [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] } ; </span>] [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>] }; zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type forward; [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] }; zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { type delegation-only; }; </pre> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2587635"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2587641"></a>Zone Types</h4></div></div></div> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="varname">master</code></p></td> <td><p>The server has a master copy of the data for the zone and will be able to provide authoritative answers for it.</p></td> </tr> <tr> <td><p><code class="varname">slave</code></p></td> <td><p>A slave zone is a replica of a master zone. The <span><strong class="command">masters</strong></span> list specifies one or more IP addresses of master servers that the slave contacts to update its copy of the zone. Masters list elements can also be names of other masters lists. By default, transfers are made from port 53 on the servers; this can be changed for all servers by specifying a port number before the list of IP addresses, or on a per-server basis after the IP address. Authentication to the master can also be done with per-server TSIG keys. If a file is specified, then the replica will be written to this file whenever the zone is changed, and reloaded from this file on a server restart. Use of a file is recommended, since it often speeds server startup and eliminates a needless waste of bandwidth. Note that for large numbers (in the tens or hundreds of thousands) of zones per server, it is best to use a two-level naming scheme for zone file names. For example, a slave server for the zone <code class="literal">example.com</code> might place the zone contents into a file called <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is just the first two letters of the zone name. (Most operating systems behave very slowly if you put 100 000 files into a single directory.)</p></td> </tr> <tr> <td><p><code class="varname">stub</code></p></td> <td> <p>A stub zone is similar to a slave zone, except that it replicates only the NS records of a master zone instead of the entire zone. Stub zones are not a standard part of the DNS; they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation. </p> <p>Stub zones can be used to eliminate the need for glue NS record in a parent zone at the expense of maintaining a stub zone entry and a set of name server addresses in <code class="filename">named.conf</code>. This usage is not recommended for new configurations, and BIND 9 supports it only in a limited way. In <acronym class="acronym">BIND</acronym> 4/8, zone transfers of a parent zone included the NS records from stub children of that zone. This meant that, in some cases, users could get away with configuring child stubs only in the master server for the parent zone. <acronym class="acronym">BIND</acronym> 9 never mixes together zone data from different zones in this way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent zone has child stub zones configured, all the slave servers for the parent zone also need to have the same child stub zones configured.</p> <p>Stub zones can also be used as a way of forcing the resolution of a given domain to use a particular set of authoritative servers. For example, the caching name servers on a private network using RFC1918 addressing may be configured with stub zones for <code class="literal">10.in-addr.arpa</code> to use a set of internal name servers as the authoritative servers for that domain.</p> </td> </tr> <tr> <td><p><code class="varname">forward</code></p></td> <td> <p>A "forward zone" is a way to configure forwarding on a per-domain basis. A <span><strong class="command">zone</strong></span> statement of type <span><strong class="command">forward</strong></span> can contain a <span><strong class="command">forward</strong></span> and/or <span><strong class="command">forwarders</strong></span> statement, which will apply to queries within the domain given by the zone name. If no <span><strong class="command">forwarders</strong></span> statement is present or an empty list for <span><strong class="command">forwarders</strong></span> is given, then no forwarding will be done for the domain, canceling the effects of any forwarders in the <span><strong class="command">options</strong></span> statement. Thus if you want to use this type of zone to change the behavior of the global <span><strong class="command">forward</strong></span> option (that is, "forward first" to, then "forward only", or vice versa, but want to use the same servers as set globally) you need to re-specify the global forwarders.</p> </td> </tr> <tr> <td><p><code class="varname">hint</code></p></td> <td><p>The initial set of root name servers is specified using a "hint zone". When the server starts up, it uses the root hints to find a root name server and get the most recent list of root name servers. If no hint zone is specified for class IN, the server uses a compiled-in default set of root servers hints. Classes other than IN have no built-in defaults hints.</p></td> </tr> <tr> <td><p><code class="varname">delegation-only</code></p></td> <td> <p>This is used to enforce the delegation-only status of infrastructure zones (e.g. COM, NET, ORG). Any answer that is received without an explicit or implicit delegation in the authority section will be treated as NXDOMAIN. This does not apply to the zone apex. This should not be applied to leaf zones.</p> <p><code class="varname">delegation-only</code> has no effect on answers received from forwarders.</p> </td> </tr> </tbody> </table></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2588084"></a>Class</h4></div></div></div> <p>The zone's name may optionally be followed by a class. If a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>), is assumed. This is correct for the vast majority of cases.</p> <p>The <code class="literal">hesiod</code> class is named for an information service from MIT's Project Athena. It is used to share information about various systems databases, such as users, groups, printers and so on. The keyword <code class="literal">HS</code> is a synonym for hesiod.</p> <p>Another MIT development is CHAOSnet, a LAN protocol created in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class.</p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2588115"></a>Zone Options</h4></div></div></div> <div class="variablelist"><dl> <dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">allow-notify</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.</p></dd> <dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">allow-query</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.</p></dd> <dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">allow-transfer</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.</p></dd> <dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt> <dd><p>Specifies which hosts are allowed to submit Dynamic DNS updates for master zones. The default is to deny updates from all hosts. Note that allowing updates based on the requestor's IP address is insecure; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for details. </p></dd> <dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt> <dd><p>Specifies a "Simple Secure Update" policy. See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>.</p></dd> <dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">allow-update-forwarding</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>.</p></dd> <dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt> <dd><p>Only meaningful if <span><strong class="command">notify</strong></span> is active for this zone. The set of machines that will receive a <code class="literal">DNS NOTIFY</code> message for this zone is made up of all the listed name servers (other than the primary master) for the zone plus any IP addresses specified with <span><strong class="command">also-notify</strong></span>. A port may be specified with each <span><strong class="command">also-notify</strong></span> address to send the notify messages to a port other than the default of 53. <span><strong class="command">also-notify</strong></span> is not meaningful for stub zones. The default is the empty list.</p></dd> <dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt> <dd><p> This option is used to restrict the character set and syntax of certain domain names in master files and/or DNS responses received from the network. The default varies according to zone type. For <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>. For <span><strong class="command">slave</strong></span> zones the default is <span><strong class="command">warn</strong></span>. </p></dd> <dt><span class="term"><span><strong class="command">database</strong></span></span></dt> <dd> <p>Specify the type of database to be used for storing the zone data. The string following the <span><strong class="command">database</strong></span> keyword is interpreted as a list of whitespace-delimited words. The first word identifies the database type, and any subsequent words are passed as arguments to the database to be interpreted in a way specific to the database type.</p> <p>The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's native in-memory red-black-tree database. This database does not take arguments.</p> <p>Other values are possible if additional database drivers have been linked into the server. Some sample drivers are included with the distribution but none are linked in by default.</p> </dd> <dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.</p></dd> <dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt> <dd><p>The flag only applies to hint and stub zones. If set to <strong class="userinput"><code>yes</code></strong>, then the zone will also be treated as if it is also a delegation-only type zone. </p></dd> <dt><span class="term"><span><strong class="command">forward</strong></span></span></dt> <dd><p>Only meaningful if the zone has a forwarders list. The <span><strong class="command">only</strong></span> value causes the lookup to fail after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would allow a normal lookup to be tried.</p></dd> <dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt> <dd><p>Used to override the list of global forwarders. If it is not specified in a zone of type <span><strong class="command">forward</strong></span>, no forwarding is done for the zone and the global options are not used.</p></dd> <dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt> <dd><p>Was used in <acronym class="acronym">BIND</acronym> 8 to specify the name of the transaction log (journal) file for dynamic update and IXFR. <acronym class="acronym">BIND</acronym> 9 ignores the option and constructs the name of the journal file by appending "<code class="filename">.jnl</code>" to the name of the zone file.</p></dd> <dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt> <dd><p>Was an undocumented option in <acronym class="acronym">BIND</acronym> 8. Ignored in <acronym class="acronym">BIND</acronym> 9.</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">max-transfer-time-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">max-transfer-idle-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">max-transfer-time-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.</p></dd> <dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">max-transfer-idle-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>.</p></dd> <dt><span class="term"><span><strong class="command">notify</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.</p></dd> <dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt> <dd><p>In <acronym class="acronym">BIND</acronym> 8, this option was intended for specifying a public zone key for verification of signatures in DNSSEC signed zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures on load and ignores the option.</p></dd> <dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt> <dd><p>If <strong class="userinput"><code>yes</code></strong>, the server will keep statistical information for this zone, which can be dumped to the <span><strong class="command">statistics-file</strong></span> defined in the server options.</p></dd> <dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>.</p></dd> <dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">alt-transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">use-alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">notify-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a> </p></dd> <dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">notify-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. </p></dd> <dt> <span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span> </dt> <dd><p> See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. </p></dd> <dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">ixfr-from-differences</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.</p></dd> <dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called “<span><strong class="command">options</strong></span> Statement Definition and Usage”</a>.</p></dd> <dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt> <dd><p>See the description of <span><strong class="command">multi-master</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>.</p></dd> </dl></div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div> <p><acronym class="acronym">BIND</acronym> 9 supports two alternative methods of granting clients the right to perform dynamic updates to a zone, configured by the <span><strong class="command">allow-update</strong></span> and <span><strong class="command">update-policy</strong></span> option, respectively.</p> <p>The <span><strong class="command">allow-update</strong></span> clause works the same way as in previous versions of <acronym class="acronym">BIND</acronym>. It grants given clients the permission to update any record of any name in the zone.</p> <p>The <span><strong class="command">update-policy</strong></span> clause is new in <acronym class="acronym">BIND</acronym> 9 and allows more fine-grained control over what updates are allowed. A set of rules is specified, where each rule either grants or denies permissions for one or more names to be updated by one or more identities. If the dynamic update request message is signed (that is, it includes either a TSIG or SIG(0) record), the identity of the signer can be determined.</p> <p>Rules are specified in the <span><strong class="command">update-policy</strong></span> zone option, and are only meaningful for master zones. When the <span><strong class="command">update-policy</strong></span> statement is present, it is a configuration error for the <span><strong class="command">allow-update</strong></span> statement to be present. The <span><strong class="command">update-policy</strong></span> statement only examines the signer of a message; the source address is not relevant.</p> <p>This is how a rule definition looks:</p> <pre class="programlisting"> ( <span><strong class="command">grant</strong></span> | <span><strong class="command">deny</strong></span> ) <em class="replaceable"><code>identity</code></em> <em class="replaceable"><code>nametype</code></em> <em class="replaceable"><code>name</code></em> [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>] </pre> <p>Each rule grants or denies privileges. Once a message has successfully matched a rule, the operation is immediately granted or denied and no further rules are examined. A rule is matched when the signer matches the identity field, the name matches the name field in accordance with the nametype field, and the type matches the types specified in the type field.</p> <p>The identity field specifies a name or a wildcard name. Normally, this is the name of the TSIG or SIG(0) key used to sign the update request. When a TKEY exchange has been used to create a shared secret, the identity of the shared secret is the same as the identity of the key used to authenticate the TKEY exchange. When the <em class="replaceable"><code>identity</code></em> field specifies a wildcard name, it is subject to DNS wildcard expansion, so the rule will apply to multiple identities. The <em class="replaceable"><code>identity</code></em> field must contain a fully qualified domain name.</p> <p>The <em class="replaceable"><code>nametype</code></em> field has 4 values: <code class="varname">name</code>, <code class="varname">subdomain</code>, <code class="varname">wildcard</code>, and <code class="varname">self</code>. </p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="varname">name</code></p></td> <td><p>Exact-match semantics. This rule matches when the name being updated is identical to the contents of the <em class="replaceable"><code>name</code></em> field.</p></td> </tr> <tr> <td><p><code class="varname">subdomain</code></p></td> <td><p>This rule matches when the name being updated is a subdomain of, or identical to, the contents of the <em class="replaceable"><code>name</code></em> field.</p></td> </tr> <tr> <td><p><code class="varname">wildcard</code></p></td> <td><p>The <em class="replaceable"><code>name</code></em> field is subject to DNS wildcard expansion, and this rule matches when the name being updated name is a valid expansion of the wildcard.</p></td> </tr> <tr> <td><p><code class="varname">self</code></p></td> <td><p>This rule matches when the name being updated matches the contents of the <em class="replaceable"><code>identity</code></em> field. The <em class="replaceable"><code>name</code></em> field is ignored, but should be the same as the <em class="replaceable"><code>identity</code></em> field. The <code class="varname">self</code> nametype is most useful when allowing using one key per name to update, where the key has the same name as the name to be updated. The <em class="replaceable"><code>identity</code></em> would be specified as <code class="constant">*</code> in this case.</p></td> </tr> </tbody> </table></div> <p>In all cases, the <em class="replaceable"><code>name</code></em> field must specify a fully qualified domain name.</p> <p>If no types are explicitly specified, this rule matches all types except SIG, NS, SOA, and NXT. Types may be specified by name, including "ANY" (ANY matches all types except NXT, which can never be updated). Note that when an attempt is made to delete all records associated with a name, the rules are checked for each existing record type. </p> </div> </div> </div> <div class="sect1" lang="en"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="id2589173"></a>Zone File</h2></div></div></div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="types_of_resource_records_and_when_to_use_them"></a>Types of Resource Records and When to Use Them</h3></div></div></div> <p>This section, largely borrowed from RFC 1034, describes the concept of a Resource Record (RR) and explains when each is used. Since the publication of RFC 1034, several new RRs have been identified and implemented in the DNS. These are also included.</p> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2589191"></a>Resource Records</h4></div></div></div> <p>A domain name identifies a node. Each node has a set of resource information, which may be empty. The set of resource information associated with a particular name is composed of separate RRs. The order of RRs in a set is not significant and need not be preserved by name servers, resolvers, or other parts of the DNS. However, sorting of multiple RRs is permitted for optimization purposes, for example, to specify that a particular nearby server be tried first. See <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a> and <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>.</p> <p>The components of a Resource Record are:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p>owner name</p></td> <td><p>the domain name where the RR is found.</p></td> </tr> <tr> <td><p>type</p></td> <td><p>an encoded 16-bit value that specifies the type of the resource record.</p></td> </tr> <tr> <td><p>TTL</p></td> <td><p>the time-to-live of the RR. This field is a 32-bit integer in units of seconds, and is primarily used by resolvers when they cache RRs. The TTL describes how long a RR can be cached before it should be discarded.</p></td> </tr> <tr> <td><p>class</p></td> <td><p>an encoded 16-bit value that identifies a protocol family or instance of a protocol.</p></td> </tr> <tr> <td><p>RDATA</p></td> <td><p>the resource data. The format of the data is type (and sometimes class) specific.</p></td> </tr> </tbody> </table></div> <p>The following are <span class="emphasis"><em>types</em></span> of valid RRs:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p>A</p></td> <td><p>a host address. In the IN class, this is a 32-bit IP address. Described in RFC 1035.</p></td> </tr> <tr> <td><p>AAAA</p></td> <td><p>IPv6 address. Described in RFC 1886.</p></td> </tr> <tr> <td><p>A6</p></td> <td><p>IPv6 address. This can be a partial address (a suffix) and an indirection to the name where the rest of the address (the prefix) can be found. Experimental. Described in RFC 2874.</p></td> </tr> <tr> <td><p>AFSDB</p></td> <td><p>location of AFS database servers. Experimental. Described in RFC 1183.</p></td> </tr> <tr> <td><p>APL</p></td> <td><p>address prefix list. Experimental. Described in RFC 3123.</p></td> </tr> <tr> <td><p>CERT</p></td> <td><p>holds a digital certificate. Described in RFC 2538.</p></td> </tr> <tr> <td><p>CNAME</p></td> <td><p>identifies the canonical name of an alias. Described in RFC 1035.</p></td> </tr> <tr> <td><p>DNAME</p></td> <td><p>Replaces the domain name specified with another name to be looked up, effectively aliasing an entire subtree of the domain name space rather than a single record as in the case of the CNAME RR. Described in RFC 2672.</p></td> </tr> <tr> <td><p>GPOS</p></td> <td><p>Specifies the global position. Superseded by LOC.</p></td> </tr> <tr> <td><p>HINFO</p></td> <td><p>identifies the CPU and OS used by a host. Described in RFC 1035.</p></td> </tr> <tr> <td><p>ISDN</p></td> <td><p>representation of ISDN addresses. Experimental. Described in RFC 1183.</p></td> </tr> <tr> <td><p>KEY</p></td> <td><p>stores a public key associated with a DNS name. Described in RFC 2535.</p></td> </tr> <tr> <td><p>KX</p></td> <td><p>identifies a key exchanger for this DNS name. Described in RFC 2230.</p></td> </tr> <tr> <td><p>LOC</p></td> <td><p>for storing GPS info. Described in RFC 1876. Experimental.</p></td> </tr> <tr> <td><p>MX</p></td> <td><p>identifies a mail exchange for the domain. A 16-bit preference value (lower is better) followed by the host name of the mail exchange. Described in RFC 974, RFC 1035.</p></td> </tr> <tr> <td><p>NAPTR</p></td> <td><p>name authority pointer. Described in RFC 2915.</p></td> </tr> <tr> <td><p>NSAP</p></td> <td><p>a network service access point. Described in RFC 1706.</p></td> </tr> <tr> <td><p>NS</p></td> <td><p>the authoritative name server for the domain. Described in RFC 1035.</p></td> </tr> <tr> <td><p>NXT</p></td> <td><p>used in DNSSEC to securely indicate that RRs with an owner name in a certain name interval do not exist in a zone and indicate what RR types are present for an existing name. Described in RFC 2535.</p></td> </tr> <tr> <td><p>PTR</p></td> <td><p>a pointer to another part of the domain name space. Described in RFC 1035.</p></td> </tr> <tr> <td><p>PX</p></td> <td><p>provides mappings between RFC 822 and X.400 addresses. Described in RFC 2163.</p></td> </tr> <tr> <td><p>RP</p></td> <td><p>information on persons responsible for the domain. Experimental. Described in RFC 1183.</p></td> </tr> <tr> <td><p>RT</p></td> <td><p>route-through binding for hosts that do not have their own direct wide area network addresses. Experimental. Described in RFC 1183.</p></td> </tr> <tr> <td><p>SIG</p></td> <td><p>("signature") contains data authenticated in the secure DNS. Described in RFC 2535.</p></td> </tr> <tr> <td><p>SOA</p></td> <td><p>identifies the start of a zone of authority. Described in RFC 1035.</p></td> </tr> <tr> <td><p>SRV</p></td> <td><p>information about well known network services (replaces WKS). Described in RFC 2782.</p></td> </tr> <tr> <td><p>TXT</p></td> <td><p>text records. Described in RFC 1035.</p></td> </tr> <tr> <td><p>WKS</p></td> <td><p>information about which well known network services, such as SMTP, that a domain supports. Historical. </p></td> </tr> <tr> <td><p>X25</p></td> <td><p>representation of X.25 network addresses. Experimental. Described in RFC 1183.</p></td> </tr> </tbody> </table></div> <p>The following <span class="emphasis"><em>classes</em></span> of resource records are currently valid in the DNS:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p>IN</p></td> <td><p>The Internet.</p></td> </tr> <tr> <td><p>CH</p></td> <td><p> CHAOSnet, a LAN protocol created at MIT in the mid-1970s. Rarely used for its historical purpose, but reused for BIND's built-in server information zones, e.g., <code class="literal">version.bind</code>. </p></td> </tr> <tr> <td><p>HS</p></td> <td><p> Hesiod, an information service developed by MIT's Project Athena. It is used to share information about various systems databases, such as users, groups, printers and so on. </p></td> </tr> </tbody> </table></div> <p>The owner name is often implicit, rather than forming an integral part of the RR. For example, many name servers internally form tree or hash structures for the name space, and chain RRs off nodes. The remaining RR parts are the fixed header (type, class, TTL) which is consistent for all RRs, and a variable part (RDATA) that fits the needs of the resource being described.</p> <p>The meaning of the TTL field is a time limit on how long an RR can be kept in a cache. This limit does not apply to authoritative data in zones; it is also timed out, but by the refreshing policies for the zone. The TTL is assigned by the administrator for the zone where the data originates. While short TTLs can be used to minimize caching, and a zero TTL prohibits caching, the realities of Internet performance suggest that these times should be on the order of days for the typical host. If a change can be anticipated, the TTL can be reduced prior to the change to minimize inconsistency during the change, and then increased back to its former value following the change.</p> <p>The data in the RDATA section of RRs is carried as a combination of binary strings and domain names. The domain names are frequently used as "pointers" to other data in the DNS.</p> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2590180"></a>Textual expression of RRs</h4></div></div></div> <p>RRs are represented in binary form in the packets of the DNS protocol, and are usually represented in highly encoded form when stored in a name server or resolver. In the examples provided in RFC 1034, a style similar to that used in master files was employed in order to show the contents of RRs. In this format, most RRs are shown on a single line, although continuation lines are possible using parentheses.</p> <p>The start of the line gives the owner of the RR. If a line begins with a blank, then the owner is assumed to be the same as that of the previous RR. Blank lines are often included for readability.</p> <p>Following the owner, we list the TTL, type, and class of the RR. Class and type use the mnemonics defined above, and TTL is an integer before the type field. In order to avoid ambiguity in parsing, type and class mnemonics are disjoint, TTLs are integers, and the type mnemonic is always last. The IN class and TTL values are often omitted from examples in the interests of clarity.</p> <p>The resource data or RDATA section of the RR are given using knowledge of the typical representation for the data.</p> <p>For example, we might show the RRs carried in a message as:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="literal">ISI.EDU.</code></p></td> <td><p><code class="literal">MX</code></p></td> <td><p><code class="literal">10 VENERA.ISI.EDU.</code></p></td> </tr> <tr> <td><p></p></td> <td><p><code class="literal">MX</code></p></td> <td><p><code class="literal">10 VAXA.ISI.EDU</code></p></td> </tr> <tr> <td><p><code class="literal">VENERA.ISI.EDU</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">128.9.0.32</code></p></td> </tr> <tr> <td><p></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">10.1.0.52</code></p></td> </tr> <tr> <td><p><code class="literal">VAXA.ISI.EDU</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">10.2.0.27</code></p></td> </tr> <tr> <td><p></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">128.9.0.33</code></p></td> </tr> </tbody> </table></div> <p>The MX RRs have an RDATA section which consists of a 16-bit number followed by a domain name. The address RRs use a standard IP address format to contain a 32-bit internet address.</p> <p>The above example shows six RRs, with two RRs at each of three domain names.</p> <p>Similarly we might see:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="literal">XX.LCS.MIT.EDU. IN</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">10.0.0.44</code></p></td> </tr> <tr> <td><p><code class="literal">CH</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">MIT.EDU. 2420</code></p></td> </tr> </tbody> </table></div> <p>This example shows two addresses for <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.</p> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2590605"></a>Discussion of MX Records</h3></div></div></div> <p>As described above, domain servers store information as a series of resource records, each of which contains a particular piece of information about a given domain name (which is usually, but not always, a host). The simplest way to think of a RR is as a typed pair of data, a domain name matched with a relevant datum, and stored with some additional type information to help systems determine when the RR is relevant.</p> <p>MX records are used to control delivery of email. The data specified in the record is a priority and a domain name. The priority controls the order in which email delivery is attempted, with the lowest number first. If two priorities are the same, a server is chosen randomly. If no servers at a given priority are responding, the mail transport agent will fall back to the next largest priority. Priority numbers do not have any absolute meaning — they are relevant only respective to other MX records for that domain name. The domain name given is the machine to which the mail will be delivered. It <span class="emphasis"><em>must</em></span> have an associated A record — CNAME is not sufficient.</p> <p>For a given domain, if there is both a CNAME record and an MX record, the MX record is in error, and will be ignored. Instead, the mail will be delivered to the server specified in the MX record pointed to by the CNAME.</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> <col> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="literal">example.com.</code></p></td> <td><p><code class="literal">IN</code></p></td> <td><p><code class="literal">MX</code></p></td> <td><p><code class="literal">10</code></p></td> <td><p><code class="literal">mail.example.com.</code></p></td> </tr> <tr> <td><p></p></td> <td><p><code class="literal">IN</code></p></td> <td><p><code class="literal">MX</code></p></td> <td><p><code class="literal">10</code></p></td> <td><p><code class="literal">mail2.example.com.</code></p></td> </tr> <tr> <td><p></p></td> <td><p><code class="literal">IN</code></p></td> <td><p><code class="literal">MX</code></p></td> <td><p><code class="literal">20</code></p></td> <td><p><code class="literal">mail.backup.org.</code></p></td> </tr> <tr> <td><p><code class="literal">mail.example.com.</code></p></td> <td><p><code class="literal">IN</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">10.0.0.1</code></p></td> <td><p></p></td> </tr> <tr> <td><p><code class="literal">mail2.example.com.</code></p></td> <td><p><code class="literal">IN</code></p></td> <td><p><code class="literal">A</code></p></td> <td><p><code class="literal">10.0.0.2</code></p></td> <td><p></p></td> </tr> </tbody> </table></div> <p>For example:</p> <p>Mail delivery will be attempted to <code class="literal">mail.example.com</code> and <code class="literal">mail2.example.com</code> (in any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will be attempted.</p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div> <p>The time-to-live of the RR field is a 32-bit integer represented in units of seconds, and is primarily used by resolvers when they cache RRs. The TTL describes how long a RR can be cached before it should be discarded. The following three types of TTL are currently used in a zone file.</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p>SOA</p></td> <td> <p>The last field in the SOA is the negative caching TTL. This controls how long other servers will cache no-such-domain (NXDOMAIN) responses from you.</p> <p>The maximum time for negative caching is 3 hours (3h).</p> </td> </tr> <tr> <td><p>$TTL</p></td> <td><p>The $TTL directive at the top of the zone file (before the SOA) gives a default TTL for every RR without a specific TTL set.</p></td> </tr> <tr> <td><p>RR TTLs</p></td> <td><p>Each RR can have a TTL as the second field in the RR, which will control how long other servers can cache the it.</p></td> </tr> </tbody> </table></div> <p>All of these TTLs default to units of seconds, though units can be explicitly specified, for example, <code class="literal">1h30m</code>. </p> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2591102"></a>Inverse Mapping in IPv4</h3></div></div></div> <p>Reverse name resolution (that is, translation from IP address to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain and PTR records. Entries in the in-addr.arpa domain are made in least-to-most significant order, read left to right. This is the opposite order to the way IP addresses are usually written. Thus, a machine with an IP address of 10.1.2.3 would have a corresponding in-addr.arpa name of 3.2.1.10.in-addr.arpa. This name should have a PTR resource record whose data field is the name of the machine or, optionally, multiple PTR records if the machine has more than one name. For example, in the [<span class="optional">example.com</span>] domain:</p> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><code class="literal">$ORIGIN</code></p></td> <td><p><code class="literal">2.1.10.in-addr.arpa</code></p></td> </tr> <tr> <td><p><code class="literal">3</code></p></td> <td><p><code class="literal">IN PTR foo.example.com.</code></p></td> </tr> </tbody> </table></div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p>The <span><strong class="command">$ORIGIN</strong></span> lines in the examples are for providing context to the examples only-they do not necessarily appear in the actual usage. They are only used here to indicate that the example is relative to the listed origin.</p> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2591208"></a>Other Zone File Directives</h3></div></div></div> <p>The Master File Format was initially defined in RFC 1035 and has subsequently been extended. While the Master File Format itself is class independent all records in a Master File must be of the same class.</p> <p>Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>, and <span><strong class="command">$TTL.</strong></span></p> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2591227"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div> <p>Syntax: <span><strong class="command">$ORIGIN </strong></span><em class="replaceable"><code>domain-name</code></em> [<span class="optional"> <em class="replaceable"><code>comment</code></em></span>]</p> <p><span><strong class="command">$ORIGIN</strong></span> sets the domain name that will be appended to any unqualified records. When a zone is first read in there is an implicit <span><strong class="command">$ORIGIN</strong></span> <<code class="varname">zone-name</code>><span><strong class="command">.</strong></span> The current <span><strong class="command">$ORIGIN</strong></span> is appended to the domain specified in the <span><strong class="command">$ORIGIN</strong></span> argument if it is not absolute.</p> <pre class="programlisting">$ORIGIN example.com. WWW CNAME MAIN-SERVER</pre> <p>is equivalent to</p> <pre class="programlisting">WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.</pre> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2591283"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div> <p>Syntax: <span><strong class="command">$INCLUDE</strong></span> <em class="replaceable"><code>filename</code></em> [<span class="optional"> <em class="replaceable"><code>origin</code></em> </span>] [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]</p> <p>Read and process the file <code class="filename">filename</code> as if it were included into the file at this point. If <span><strong class="command">origin</strong></span> is specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is used.</p> <p>The origin and the current domain name revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once the file has been read.</p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> RFC 1035 specifies that the current origin should be restored after an <span><strong class="command">$INCLUDE</strong></span>, but it is silent on whether the current domain name should also be restored. BIND 9 restores both of them. This could be construed as a deviation from RFC 1035, a feature, or both. </p> </div> </div> <div class="sect3" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="id2591346"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div> <p>Syntax: <span><strong class="command">$TTL</strong></span> <em class="replaceable"><code>default-ttl</code></em> [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]</p> <p>Set the default Time To Live (TTL) for subsequent records with undefined TTLs. Valid TTLs are of the range 0-2147483647 seconds.</p> <p><span><strong class="command">$TTL</strong></span> is defined in RFC 2308.</p> </div> </div> <div class="sect2" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2591377"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div> <p>Syntax: <span><strong class="command">$GENERATE</strong></span> <em class="replaceable"><code>range</code></em> <em class="replaceable"><code>lhs</code></em> [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>] [<span class="optional"><em class="replaceable"><code>class</code></em></span>] <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>rhs</code></em> [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]</p> <p><span><strong class="command">$GENERATE</strong></span> is used to create a series of resource records that only differ from each other by an iterator. <span><strong class="command">$GENERATE</strong></span> can be used to easily generate the sets of records required to support sub /24 reverse delegations described in RFC 2317: Classless IN-ADDR.ARPA delegation.</p> <pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA. $GENERATE 1-2 0 NS SERVER$.EXAMPLE. $GENERATE 1-127 $ CNAME $.0</pre> <p>is equivalent to</p> <pre class="programlisting">0.0.0.192.IN-ADDR.ARPA NS SERVER1.EXAMPLE. 0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE. 1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA. 2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA. ... 127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA. </pre> <div class="informaltable"><table border="1"> <colgroup> <col> <col> </colgroup> <tbody> <tr> <td><p><span><strong class="command">range</strong></span></p></td> <td><p>This can be one of two forms: start-stop or start-stop/step. If the first form is used, then step is set to 1. All of start, stop and step must be positive.</p></td> </tr> <tr> <td><p><span><strong class="command">lhs</strong></span></p></td> <td> <p><span><strong class="command">lhs</strong></span> describes the owner name of the resource records to be created. Any single <span><strong class="command">$</strong></span> (dollar sign) symbols within the <span><strong class="command">lhs</strong></span> side are replaced by the iterator value. To get a $ in the output you need to escape the <span><strong class="command">$</strong></span> using a backslash <span><strong class="command">\</strong></span>, e.g. <span><strong class="command">\$</strong></span>. The <span><strong class="command">$</strong></span> may optionally be followed by modifiers which change the offset from the iterator, field width and base. Modifiers are introduced by a <span><strong class="command">{</strong></span> immediately following the <span><strong class="command">$</strong></span> as <span><strong class="command">${offset[,width[,base]]}</strong></span>. For example, <span><strong class="command">${-20,3,d}</strong></span> which subtracts 20 from the current value, prints the result as a decimal in a zero-padded field of width 3. Available output forms are decimal (<span><strong class="command">d</strong></span>), octal (<span><strong class="command">o</strong></span>) and hexadecimal (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span> for uppercase). The default modifier is <span><strong class="command">${0,0,d}</strong></span>. If the <span><strong class="command">lhs</strong></span> is not absolute, the current <span><strong class="command">$ORIGIN</strong></span> is appended to the name.</p> <p>For compatibility with earlier versions, <span><strong class="command">$$</strong></span> is still recognized as indicating a literal $ in the output.</p> </td> </tr> <tr> <td><p><span><strong class="command">ttl</strong></span></p></td> <td> <p>Specifies the ttl of the generated records. If not specified this will be inherited using the normal ttl inheritance rules.</p> <p><span><strong class="command">class</strong></span> and <span><strong class="command">ttl</strong></span> can be entered in either order.</p> </td> </tr> <tr> <td><p><span><strong class="command">class</strong></span></p></td> <td> <p>Specifies the class of the generated records. This must match the zone class if it is specified.</p> <p><span><strong class="command">class</strong></span> and <span><strong class="command">ttl</strong></span> can be entered in either order.</p> </td> </tr> <tr> <td><p><span><strong class="command">type</strong></span></p></td> <td><p>At present the only supported types are PTR, CNAME, DNAME, A, AAAA and NS.</p></td> </tr> <tr> <td><p><span><strong class="command">rhs</strong></span></p></td> <td><p>A domain name. It is processed similarly to lhs.</p></td> </tr> </tbody> </table></div> <p>The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension and not part of the standard zone file format.</p> <p>BIND 8 does not support the optional TTL and CLASS fields.</p> </div> </div> </div> <div class="navfooter"> <hr> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"> <a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td> <td width="20%" align="center"> </td> <td width="40%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a> </td> </tr> <tr> <td width="40%" align="left" valign="top">Chapter 5. 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