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IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR - PERFORMANCE OF THIS SOFTWARE. --> <!-- $Id: dig.html,v 1.6.2.4.2.15 2006/06/29 13:02:30 marka Exp $ --> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>dig</title> <meta name="generator" content="DocBook XSL Stylesheets V1.70.1"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en"> <a name="id2482688"></a><div class="titlepage"></div> <div class="refnamediv"> <h2>Name</h2> <p>dig — DNS lookup utility</p> </div> <div class="refsynopsisdiv"> <h2>Synopsis</h2> <div class="cmdsynopsis"><p><code class="command">dig</code> [@server] [<code class="option">-b <em class="replaceable"><code>address</code></em></code>] [<code class="option">-c <em class="replaceable"><code>class</code></em></code>] [<code class="option">-f <em class="replaceable"><code>filename</code></em></code>] [<code class="option">-k <em class="replaceable"><code>filename</code></em></code>] [<code class="option">-p <em class="replaceable"><code>port#</code></em></code>] [<code class="option">-t <em class="replaceable"><code>type</code></em></code>] [<code class="option">-x <em class="replaceable"><code>addr</code></em></code>] [<code class="option">-y <em class="replaceable"><code>name:key</code></em></code>] [<code class="option">-4</code>] [<code class="option">-6</code>] [name] [type] [class] [queryopt...]</p></div> <div class="cmdsynopsis"><p><code class="command">dig</code> [<code class="option">-h</code>]</p></div> <div class="cmdsynopsis"><p><code class="command">dig</code> [global-queryopt...] [query...]</p></div> </div> <div class="refsect1" lang="en"> <a name="id2549541"></a><h2>DESCRIPTION</h2> <p> <span><strong class="command">dig</strong></span> (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried. Most DNS administrators use <span><strong class="command">dig</strong></span> to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than <span><strong class="command">dig</strong></span>. </p> <p> Although <span><strong class="command">dig</strong></span> is normally used with command-line arguments, it also has a batch mode of operation for reading lookup requests from a file. A brief summary of its command-line arguments and options is printed when the <code class="option">-h</code> option is given. Unlike earlier versions, the BIND9 implementation of <span><strong class="command">dig</strong></span> allows multiple lookups to be issued from the command line. </p> <p> Unless it is told to query a specific name server, <span><strong class="command">dig</strong></span> will try each of the servers listed in <code class="filename">/etc/resolv.conf</code>. </p> <p> When no command line arguments or options are given, will perform an NS query for "." (the root). </p> <p> It is possible to set per-user defaults for <span><strong class="command">dig</strong></span> via <code class="filename">${HOME}/.digrc</code>. This file is read and any options in it are applied before the command line arguments. </p> </div> <div class="refsect1" lang="en"> <a name="id2549600"></a><h2>SIMPLE USAGE</h2> <p> A typical invocation of <span><strong class="command">dig</strong></span> looks like: </p> <pre class="programlisting"> dig @server name type </pre> <p> where: </p> <div class="variablelist"><dl> <dt><span class="term"><code class="constant">server</code></span></dt> <dd><p> is the name or IP address of the name server to query. This can be an IPv4 address in dotted-decimal notation or an IPv6 address in colon-delimited notation. When the supplied <em class="parameter"><code>server</code></em> argument is a hostname, <span><strong class="command">dig</strong></span> resolves that name before querying that name server. If no <em class="parameter"><code>server</code></em> argument is provided, <span><strong class="command">dig</strong></span> consults <code class="filename">/etc/resolv.conf</code> and queries the name servers listed there. The reply from the name server that responds is displayed. </p></dd> <dt><span class="term"><code class="constant">name</code></span></dt> <dd><p> is the name of the resource record that is to be looked up. </p></dd> <dt><span class="term"><code class="constant">type</code></span></dt> <dd><p> indicates what type of query is required — ANY, A, MX, SIG, etc. <em class="parameter"><code>type</code></em> can be any valid query type. If no <em class="parameter"><code>type</code></em> argument is supplied, <span><strong class="command">dig</strong></span> will perform a lookup for an A record. </p></dd> </dl></div> <p> </p> </div> <div class="refsect1" lang="en"> <a name="id2549747"></a><h2>OPTIONS</h2> <p> The <code class="option">-b</code> option sets the source IP address of the query to <em class="parameter"><code>address</code></em>. This must be a valid address on one of the host's network interfaces or "0.0.0.0" or "::". An optional port may be specified by appending "#<port>" </p> <p> The default query class (IN for internet) is overridden by the <code class="option">-c</code> option. <em class="parameter"><code>class</code></em> is any valid class, such as HS for Hesiod records or CH for CHAOSNET records. </p> <p> The <code class="option">-f</code> option makes <span><strong class="command">dig </strong></span> operate in batch mode by reading a list of lookup requests to process from the file <em class="parameter"><code>filename</code></em>. The file contains a number of queries, one per line. Each entry in the file should be organised in the same way they would be presented as queries to <span><strong class="command">dig</strong></span> using the command-line interface. </p> <p> If a non-standard port number is to be queried, the <code class="option">-p</code> option is used. <em class="parameter"><code>port#</code></em> is the port number that <span><strong class="command">dig</strong></span> will send its queries instead of the standard DNS port number 53. This option would be used to test a name server that has been configured to listen for queries on a non-standard port number. </p> <p> The <code class="option">-4</code> option forces <span><strong class="command">dig</strong></span> to only use IPv4 query transport. The <code class="option">-6</code> option forces <span><strong class="command">dig</strong></span> to only use IPv6 query transport. </p> <p> The <code class="option">-t</code> option sets the query type to <em class="parameter"><code>type</code></em>. It can be any valid query type which is supported in BIND9. The default query type "A", unless the <code class="option">-x</code> option is supplied to indicate a reverse lookup. A zone transfer can be requested by specifying a type of AXFR. When an incremental zone transfer (IXFR) is required, <em class="parameter"><code>type</code></em> is set to <code class="literal">ixfr=N</code>. The incremental zone transfer will contain the changes made to the zone since the serial number in the zone's SOA record was <em class="parameter"><code>N</code></em>. </p> <p> Reverse lookups - mapping addresses to names - are simplified by the <code class="option">-x</code> option. <em class="parameter"><code>addr</code></em> is an IPv4 address in dotted-decimal notation, or a colon-delimited IPv6 address. When this option is used, there is no need to provide the <em class="parameter"><code>name</code></em>, <em class="parameter"><code>class</code></em> and <em class="parameter"><code>type</code></em> arguments. <span><strong class="command">dig</strong></span> automatically performs a lookup for a name like <code class="literal">11.12.13.10.in-addr.arpa</code> and sets the query type and class to PTR and IN respectively. By default, IPv6 addresses are looked up using nibble format under the IP6.ARPA domain. To use the older RFC1886 method using the IP6.INT domain specify the <code class="option">-i</code> option. Bit string labels (RFC2874) are now experimental and are not attempted. </p> <p> To sign the DNS queries sent by <span><strong class="command">dig</strong></span> and their responses using transaction signatures (TSIG), specify a TSIG key file using the <code class="option">-k</code> option. You can also specify the TSIG key itself on the command line using the <code class="option">-y</code> option; <em class="parameter"><code>name</code></em> is the name of the TSIG key and <em class="parameter"><code>key</code></em> is the actual key. The key is a base-64 encoded string, typically generated by <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>. Caution should be taken when using the <code class="option">-y</code> option on multi-user systems as the key can be visible in the output from <span class="citerefentry"><span class="refentrytitle">ps</span>(1 )</span> or in the shell's history file. When using TSIG authentication with <span><strong class="command">dig</strong></span>, the name server that is queried needs to know the key and algorithm that is being used. In BIND, this is done by providing appropriate <span><strong class="command">key</strong></span> and <span><strong class="command">server</strong></span> statements in <code class="filename">named.conf</code>. </p> </div> <div class="refsect1" lang="en"> <a name="id2549998"></a><h2>QUERY OPTIONS</h2> <p> <span><strong class="command">dig</strong></span> provides a number of query options which affect the way in which lookups are made and the results displayed. Some of these set or reset flag bits in the query header, some determine which sections of the answer get printed, and others determine the timeout and retry strategies. </p> <p> Each query option is identified by a keyword preceded by a plus sign (<code class="literal">+</code>). Some keywords set or reset an option. These may be preceded by the string <code class="literal">no</code> to negate the meaning of that keyword. Other keywords assign values to options like the timeout interval. They have the form <code class="option">+keyword=value</code>. The query options are: </p> <div class="variablelist"><dl> <dt><span class="term"><code class="option">+[no]tcp</code></span></dt> <dd><p> Use [do not use] TCP when querying name servers. The default behaviour is to use UDP unless an AXFR or IXFR query is requested, in which case a TCP connection is used. </p></dd> <dt><span class="term"><code class="option">+[no]vc</code></span></dt> <dd><p> Use [do not use] TCP when querying name servers. This alternate syntax to <em class="parameter"><code>+[no]tcp</code></em> is provided for backwards compatibility. The "vc" stands for "virtual circuit". </p></dd> <dt><span class="term"><code class="option">+[no]ignore</code></span></dt> <dd><p> Ignore truncation in UDP responses instead of retrying with TCP. By default, TCP retries are performed. </p></dd> <dt><span class="term"><code class="option">+domain=somename</code></span></dt> <dd><p> Set the search list to contain the single domain <em class="parameter"><code>somename</code></em>, as if specified in a <span><strong class="command">domain</strong></span> directive in <code class="filename">/etc/resolv.conf</code>, and enable search list processing as if the <em class="parameter"><code>+search</code></em> option were given. </p></dd> <dt><span class="term"><code class="option">+[no]search</code></span></dt> <dd><p> Use [do not use] the search list defined by the searchlist or domain directive in <code class="filename">resolv.conf</code> (if any). The search list is not used by default. </p></dd> <dt><span class="term"><code class="option">+[no]defname</code></span></dt> <dd><p> Deprecated, treated as a synonym for <em class="parameter"><code>+[no]search</code></em> </p></dd> <dt><span class="term"><code class="option">+[no]aaonly</code></span></dt> <dd><p> Sets the "aa" flag in the query. </p></dd> <dt><span class="term"><code class="option">+[no]aaflag</code></span></dt> <dd><p> A synonym for <em class="parameter"><code>+[no]aaonly</code></em>. </p></dd> <dt><span class="term"><code class="option">+[no]adflag</code></span></dt> <dd><p> Set [do not set] the AD (authentic data) bit in the query. The AD bit currently has a standard meaning only in responses, not in queries, but the ability to set the bit in the query is provided for completeness. </p></dd> <dt><span class="term"><code class="option">+[no]cdflag</code></span></dt> <dd><p> Set [do not set] the CD (checking disabled) bit in the query. This requests the server to not perform DNSSEC validation of responses. </p></dd> <dt><span class="term"><code class="option">+[no]cl</code></span></dt> <dd><p> Display [do not display] the CLASS when printing the record. </p></dd> <dt><span class="term"><code class="option">+[no]ttlid</code></span></dt> <dd><p> Display [do not display] the TTL when printing the record. </p></dd> <dt><span class="term"><code class="option">+[no]recurse</code></span></dt> <dd><p> Toggle the setting of the RD (recursion desired) bit in the query. This bit is set by default, which means <span><strong class="command">dig</strong></span> normally sends recursive queries. Recursion is automatically disabled when the <em class="parameter"><code>+nssearch</code></em> or <em class="parameter"><code>+trace</code></em> query options are used. </p></dd> <dt><span class="term"><code class="option">+[no]nssearch</code></span></dt> <dd><p> When this option is set, <span><strong class="command">dig</strong></span> attempts to find the authoritative name servers for the zone containing the name being looked up and display the SOA record that each name server has for the zone. </p></dd> <dt><span class="term"><code class="option">+[no]trace</code></span></dt> <dd><p> Toggle tracing of the delegation path from the root name servers for the name being looked up. Tracing is disabled by default. When tracing is enabled, <span><strong class="command">dig</strong></span> makes iterative queries to resolve the name being looked up. It will follow referrals from the root servers, showing the answer from each server that was used to resolve the lookup. </p></dd> <dt><span class="term"><code class="option">+[no]cmd</code></span></dt> <dd><p> toggles the printing of the initial comment in the output identifying the version of <span><strong class="command">dig</strong></span> and the query options that have been applied. This comment is printed by default. </p></dd> <dt><span class="term"><code class="option">+[no]short</code></span></dt> <dd><p> Provide a terse answer. The default is to print the answer in a verbose form. </p></dd> <dt><span class="term"><code class="option">+[no]identify</code></span></dt> <dd><p> Show [or do not show] the IP address and port number that supplied the answer when the <em class="parameter"><code>+short</code></em> option is enabled. If short form answers are requested, the default is not to show the source address and port number of the server that provided the answer. </p></dd> <dt><span class="term"><code class="option">+[no]comments</code></span></dt> <dd><p> Toggle the display of comment lines in the output. The default is to print comments. </p></dd> <dt><span class="term"><code class="option">+[no]stats</code></span></dt> <dd><p> This query option toggles the printing of statistics: when the query was made, the size of the reply and so on. The default behaviour is to print the query statistics. </p></dd> <dt><span class="term"><code class="option">+[no]qr</code></span></dt> <dd><p> Print [do not print] the query as it is sent. By default, the query is not printed. </p></dd> <dt><span class="term"><code class="option">+[no]question</code></span></dt> <dd><p> Print [do not print] the question section of a query when an answer is returned. The default is to print the question section as a comment. </p></dd> <dt><span class="term"><code class="option">+[no]answer</code></span></dt> <dd><p> Display [do not display] the answer section of a reply. The default is to display it. </p></dd> <dt><span class="term"><code class="option">+[no]authority</code></span></dt> <dd><p> Display [do not display] the authority section of a reply. The default is to display it. </p></dd> <dt><span class="term"><code class="option">+[no]additional</code></span></dt> <dd><p> Display [do not display] the additional section of a reply. The default is to display it. </p></dd> <dt><span class="term"><code class="option">+[no]all</code></span></dt> <dd><p> Set or clear all display flags. </p></dd> <dt><span class="term"><code class="option">+time=T</code></span></dt> <dd><p> Sets the timeout for a query to <em class="parameter"><code>T</code></em> seconds. The default time out is 5 seconds. An attempt to set <em class="parameter"><code>T</code></em> to less than 1 will result in a query timeout of 1 second being applied. </p></dd> <dt><span class="term"><code class="option">+tries=T</code></span></dt> <dd><p> Sets the number of times to try UDP queries to server to <em class="parameter"><code>T</code></em> instead of the default, 3. If <em class="parameter"><code>T</code></em> is less than or equal to zero, the number of tries is silently rounded up to 1. </p></dd> <dt><span class="term"><code class="option">+retry=T</code></span></dt> <dd><p> Sets the number of times to retry UDP queries to server to <em class="parameter"><code>T</code></em> instead of the default, 2. Unlike <em class="parameter"><code>+tries</code></em>, this does not include the initial query. </p></dd> <dt><span class="term"><code class="option">+ndots=D</code></span></dt> <dd><p> Set the number of dots that have to appear in <em class="parameter"><code>name</code></em> to <em class="parameter"><code>D</code></em> for it to be considered absolute. The default value is that defined using the ndots statement in <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots statement is present. Names with fewer dots are interpreted as relative names and will be searched for in the domains listed in the <code class="option">search</code> or <code class="option">domain</code> directive in <code class="filename">/etc/resolv.conf</code>. </p></dd> <dt><span class="term"><code class="option">+bufsize=B</code></span></dt> <dd><p> Set the UDP message buffer size advertised using EDNS0 to <em class="parameter"><code>B</code></em> bytes. The maximum and minimum sizes of this buffer are 65535 and 0 respectively. Values outside this range are rounded up or down appropriately. </p></dd> <dt><span class="term"><code class="option">+[no]multiline</code></span></dt> <dd><p> Print records like the SOA records in a verbose multi-line format with human-readable comments. The default is to print each record on a single line, to facilitate machine parsing of the <span><strong class="command">dig</strong></span> output. </p></dd> <dt><span class="term"><code class="option">+[no]fail</code></span></dt> <dd><p> Do not try the next server if you receive a SERVFAIL. The default is to not try the next server which is the reverse of normal stub resolver behaviour. </p></dd> <dt><span class="term"><code class="option">+[no]besteffort</code></span></dt> <dd><p> Attempt to display the contents of messages which are malformed. The default is to not display malformed answers. </p></dd> <dt><span class="term"><code class="option">+[no]dnssec</code></span></dt> <dd><p> Requests DNSSEC records be sent by setting the DNSSEC OK bit (DO) in the OPT record in the additional section of the query. </p></dd> <dt><span class="term"><code class="option">+[no]sigchase</code></span></dt> <dd><p> Chase DNSSEC signature chains. Requires dig be compiled with -DDIG_SIGCHASE. </p></dd> <dt><span class="term"><code class="option">+trusted-key=####</code></span></dt> <dd> <p> Specifies a file containing trusted keys to be used with <code class="option">+sigchase</code>. Each DNSKEY record must be on its own line. </p> <p> If not specified <span><strong class="command">dig</strong></span> will look for <code class="filename">/etc/trusted-key.key</code> then <code class="filename">trusted-key.key</code> in the current directory. </p> <p> Requires dig be compiled with -DDIG_SIGCHASE. </p> </dd> <dt><span class="term"><code class="option">+[no]topdown</code></span></dt> <dd><p> When chasing DNSSEC signature chains perform a top down validation. Requires dig be compiled with -DDIG_SIGCHASE. </p></dd> </dl></div> <p> </p> </div> <div class="refsect1" lang="en"> <a name="id2550666"></a><h2>MULTIPLE QUERIES</h2> <p> The BIND 9 implementation of <span><strong class="command">dig </strong></span> supports specifying multiple queries on the command line (in addition to supporting the <code class="option">-f</code> batch file option). Each of those queries can be supplied with its own set of flags, options and query options. </p> <p> In this case, each <em class="parameter"><code>query</code></em> argument represent an individual query in the command-line syntax described above. Each consists of any of the standard options and flags, the name to be looked up, an optional query type and class and any query options that should be applied to that query. </p> <p> A global set of query options, which should be applied to all queries, can also be supplied. These global query options must precede the first tuple of name, class, type, options, flags, and query options supplied on the command line. Any global query options (except the <code class="option">+[no]cmd</code> option) can be overridden by a query-specific set of query options. For example: </p> <pre class="programlisting"> dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr </pre> <p> shows how <span><strong class="command">dig</strong></span> could be used from the command line to make three lookups: an ANY query for <code class="literal">www.isc.org</code>, a reverse lookup of 127.0.0.1 and a query for the NS records of <code class="literal">isc.org</code>. A global query option of <em class="parameter"><code>+qr</code></em> is applied, so that <span><strong class="command">dig</strong></span> shows the initial query it made for each lookup. The final query has a local query option of <em class="parameter"><code>+noqr</code></em> which means that <span><strong class="command">dig</strong></span> will not print the initial query when it looks up the NS records for <code class="literal">isc.org</code>. </p> </div> <div class="refsect1" lang="en"> <a name="id2550725"></a><h2>FILES</h2> <p> <code class="filename">/etc/resolv.conf</code> </p> <p> <code class="filename">${HOME}/.digrc</code> </p> </div> <div class="refsect1" lang="en"> <a name="id2550744"></a><h2>SEE ALSO</h2> <p> <span class="citerefentry"><span class="refentrytitle">host</span>(1)</span>, <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>, <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>, <em class="citetitle">RFC1035</em>. </p> </div> <div class="refsect1" lang="en"> <a name="id2550782"></a><h2>BUGS </h2> <p> There are probably too many query options. </p> </div> </div></body> </html>