1 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
3 [<!ENTITY mdash "—">]>
5 - Copyright (C) 2004-2010, 2013 Internet Systems Consortium, Inc. ("ISC")
6 - Copyright (C) 2000-2003 Internet Software Consortium.
8 - Permission to use, copy, modify, and/or distribute this software for any
9 - purpose with or without fee is hereby granted, provided that the above
10 - copyright notice and this permission notice appear in all copies.
12 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
13 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
14 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
15 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
16 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
17 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
18 - PERFORMANCE OF THIS SOFTWARE.
21 <!-- $Id: dig.docbook,v 1.47 2010/03/04 23:50:34 tbox Exp $ -->
22 <refentry id="man.dig">
25 <date>June 30, 2000</date>
29 <refentrytitle>dig</refentrytitle>
30 <manvolnum>1</manvolnum>
31 <refmiscinfo>BIND9</refmiscinfo>
35 <refname>dig</refname>
36 <refpurpose>DNS lookup utility</refpurpose>
49 <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
56 <holder>Internet Software Consortium.</holder>
62 <command>dig</command>
63 <arg choice="opt">@server</arg>
64 <arg><option>-b <replaceable class="parameter">address</replaceable></option></arg>
65 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
66 <arg><option>-f <replaceable class="parameter">filename</replaceable></option></arg>
67 <arg><option>-k <replaceable class="parameter">filename</replaceable></option></arg>
68 <arg><option>-m</option></arg>
69 <arg><option>-p <replaceable class="parameter">port#</replaceable></option></arg>
70 <arg><option>-q <replaceable class="parameter">name</replaceable></option></arg>
71 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
72 <arg><option>-x <replaceable class="parameter">addr</replaceable></option></arg>
73 <arg><option>-y <replaceable class="parameter"><optional>hmac:</optional>name:key</replaceable></option></arg>
74 <arg><option>-4</option></arg>
75 <arg><option>-6</option></arg>
76 <arg choice="opt">name</arg>
77 <arg choice="opt">type</arg>
78 <arg choice="opt">class</arg>
79 <arg choice="opt" rep="repeat">queryopt</arg>
83 <command>dig</command>
84 <arg><option>-h</option></arg>
88 <command>dig</command>
89 <arg choice="opt" rep="repeat">global-queryopt</arg>
90 <arg choice="opt" rep="repeat">query</arg>
95 <title>DESCRIPTION</title>
96 <para><command>dig</command>
97 (domain information groper) is a flexible tool
98 for interrogating DNS name servers. It performs DNS lookups and
99 displays the answers that are returned from the name server(s) that
100 were queried. Most DNS administrators use <command>dig</command> to
101 troubleshoot DNS problems because of its flexibility, ease of use and
102 clarity of output. Other lookup tools tend to have less functionality
103 than <command>dig</command>.
107 Although <command>dig</command> is normally used with
109 arguments, it also has a batch mode of operation for reading lookup
110 requests from a file. A brief summary of its command-line arguments
111 and options is printed when the <option>-h</option> option is given.
112 Unlike earlier versions, the BIND 9 implementation of
113 <command>dig</command> allows multiple lookups to be issued
119 Unless it is told to query a specific name server,
120 <command>dig</command> will try each of the servers listed in
121 <filename>/etc/resolv.conf</filename>. If no usable server addresses
122 are found, <command>dig</command> will send the query to the local
127 When no command line arguments or options are given,
128 <command>dig</command> will perform an NS query for "." (the root).
132 It is possible to set per-user defaults for <command>dig</command> via
133 <filename>${HOME}/.digrc</filename>. This file is read and
135 are applied before the command line arguments.
139 The IN and CH class names overlap with the IN and CH top level
140 domains names. Either use the <option>-t</option> and
141 <option>-c</option> options to specify the type and class,
142 use the <option>-q</option> the specify the domain name, or
143 use "IN." and "CH." when looking up these top level domains.
149 <title>SIMPLE USAGE</title>
152 A typical invocation of <command>dig</command> looks like:
153 <programlisting> dig @server name type </programlisting>
159 <term><constant>server</constant></term>
162 is the name or IP address of the name server to query. This
163 can be an IPv4 address in dotted-decimal notation or an IPv6
164 address in colon-delimited notation. When the supplied
165 <parameter>server</parameter> argument is a hostname,
166 <command>dig</command> resolves that name before querying
170 If no <parameter>server</parameter> argument is
171 provided, <command>dig</command> consults
172 <filename>/etc/resolv.conf</filename>; if an
173 address is found there, it queries the name server at
174 that address. If either of the <option>-4</option> or
175 <option>-6</option> options are in use, then
176 only addresses for the corresponding transport
177 will be tried. If no usable addresses are found,
178 <command>dig</command> will send the query to the
179 local host. The reply from the name server that
180 responds is displayed.
186 <term><constant>name</constant></term>
189 is the name of the resource record that is to be looked up.
195 <term><constant>type</constant></term>
198 indicates what type of query is required —
199 ANY, A, MX, SIG, etc.
200 <parameter>type</parameter> can be any valid query
202 <parameter>type</parameter> argument is supplied,
203 <command>dig</command> will perform a lookup for an
215 <title>OPTIONS</title>
218 The <option>-b</option> option sets the source IP address of the query
219 to <parameter>address</parameter>. This must be a valid
221 one of the host's network interfaces or "0.0.0.0" or "::". An optional
223 may be specified by appending "#<port>"
227 The default query class (IN for internet) is overridden by the
228 <option>-c</option> option. <parameter>class</parameter> is
230 class, such as HS for Hesiod records or CH for Chaosnet records.
234 The <option>-f</option> option makes <command>dig </command>
236 in batch mode by reading a list of lookup requests to process from the
237 file <parameter>filename</parameter>. The file contains a
239 queries, one per line. Each entry in the file should be organized in
240 the same way they would be presented as queries to
241 <command>dig</command> using the command-line interface.
245 The <option>-m</option> option enables memory usage debugging.
246 <!-- It enables ISC_MEM_DEBUGTRACE and ISC_MEM_DEBUGRECORD
247 documented in include/isc/mem.h -->
251 If a non-standard port number is to be queried, the
252 <option>-p</option> option is used. <parameter>port#</parameter> is
253 the port number that <command>dig</command> will send its
255 instead of the standard DNS port number 53. This option would be used
256 to test a name server that has been configured to listen for queries
257 on a non-standard port number.
261 The <option>-4</option> option forces <command>dig</command>
263 use IPv4 query transport. The <option>-6</option> option forces
264 <command>dig</command> to only use IPv6 query transport.
268 The <option>-t</option> option sets the query type to
269 <parameter>type</parameter>. It can be any valid query type
271 supported in BIND 9. The default query type is "A", unless the
272 <option>-x</option> option is supplied to indicate a reverse lookup.
273 A zone transfer can be requested by specifying a type of AXFR. When
274 an incremental zone transfer (IXFR) is required,
275 <parameter>type</parameter> is set to <literal>ixfr=N</literal>.
276 The incremental zone transfer will contain the changes made to the zone
277 since the serial number in the zone's SOA record was
278 <parameter>N</parameter>.
282 The <option>-q</option> option sets the query name to
283 <parameter>name</parameter>. This useful do distinguish the
284 <parameter>name</parameter> from other arguments.
288 Reverse lookups — mapping addresses to names — are simplified by the
289 <option>-x</option> option. <parameter>addr</parameter> is
291 address in dotted-decimal notation, or a colon-delimited IPv6 address.
292 When this option is used, there is no need to provide the
293 <parameter>name</parameter>, <parameter>class</parameter> and
294 <parameter>type</parameter> arguments. <command>dig</command>
295 automatically performs a lookup for a name like
296 <literal>11.12.13.10.in-addr.arpa</literal> and sets the
298 class to PTR and IN respectively. By default, IPv6 addresses are
299 looked up using nibble format under the IP6.ARPA domain.
300 To use the older RFC1886 method using the IP6.INT domain
301 specify the <option>-i</option> option. Bit string labels (RFC2874)
302 are now experimental and are not attempted.
306 To sign the DNS queries sent by <command>dig</command> and
308 responses using transaction signatures (TSIG), specify a TSIG key file
309 using the <option>-k</option> option. You can also specify the TSIG
310 key itself on the command line using the <option>-y</option> option;
311 <parameter>hmac</parameter> is the type of the TSIG, default HMAC-MD5,
312 <parameter>name</parameter> is the name of the TSIG key and
313 <parameter>key</parameter> is the actual key. The key is a
315 encoded string, typically generated by
317 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
320 Caution should be taken when using the <option>-y</option> option on
321 multi-user systems as the key can be visible in the output from
323 <refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum>
325 or in the shell's history file. When
326 using TSIG authentication with <command>dig</command>, the name
327 server that is queried needs to know the key and algorithm that is
328 being used. In BIND, this is done by providing appropriate
329 <command>key</command> and <command>server</command> statements in
330 <filename>named.conf</filename>.
336 <title>QUERY OPTIONS</title>
338 <para><command>dig</command>
339 provides a number of query options which affect
340 the way in which lookups are made and the results displayed. Some of
341 these set or reset flag bits in the query header, some determine which
342 sections of the answer get printed, and others determine the timeout
343 and retry strategies.
347 Each query option is identified by a keyword preceded by a plus sign
348 (<literal>+</literal>). Some keywords set or reset an
349 option. These may be preceded
350 by the string <literal>no</literal> to negate the meaning of
352 keywords assign values to options like the timeout interval. They
353 have the form <option>+keyword=value</option>.
354 The query options are:
359 <term><option>+[no]tcp</option></term>
362 Use [do not use] TCP when querying name servers. The default
363 behavior is to use UDP unless an AXFR or IXFR query is
365 which case a TCP connection is used.
371 <term><option>+[no]vc</option></term>
374 Use [do not use] TCP when querying name servers. This alternate
375 syntax to <parameter>+[no]tcp</parameter> is
376 provided for backwards
377 compatibility. The "vc" stands for "virtual circuit".
383 <term><option>+[no]ignore</option></term>
386 Ignore truncation in UDP responses instead of retrying with TCP.
388 default, TCP retries are performed.
394 <term><option>+domain=somename</option></term>
397 Set the search list to contain the single domain
398 <parameter>somename</parameter>, as if specified in
400 <command>domain</command> directive in
401 <filename>/etc/resolv.conf</filename>, and enable
403 processing as if the <parameter>+search</parameter>
410 <term><option>+[no]search</option></term>
413 Use [do not use] the search list defined by the searchlist or
415 directive in <filename>resolv.conf</filename> (if
417 The search list is not used by default.
423 <term><option>+[no]showsearch</option></term>
426 Perform [do not perform] a search showing intermediate
433 <term><option>+[no]defname</option></term>
436 Deprecated, treated as a synonym for <parameter>+[no]search</parameter>
442 <term><option>+[no]aaonly</option></term>
445 Sets the "aa" flag in the query.
451 <term><option>+[no]aaflag</option></term>
454 A synonym for <parameter>+[no]aaonly</parameter>.
460 <term><option>+[no]adflag</option></term>
463 Set [do not set] the AD (authentic data) bit in the
464 query. This requests the server to return whether
465 all of the answer and authority sections have all
466 been validated as secure according to the security
467 policy of the server. AD=1 indicates that all records
468 have been validated as secure and the answer is not
469 from a OPT-OUT range. AD=0 indicate that some part
470 of the answer was insecure or not validated.
476 <term><option>+[no]cdflag</option></term>
479 Set [do not set] the CD (checking disabled) bit in the query.
481 requests the server to not perform DNSSEC validation of
488 <term><option>+[no]cl</option></term>
491 Display [do not display] the CLASS when printing the record.
497 <term><option>+[no]ttlid</option></term>
500 Display [do not display] the TTL when printing the record.
506 <term><option>+[no]recurse</option></term>
509 Toggle the setting of the RD (recursion desired) bit in the
511 This bit is set by default, which means <command>dig</command>
512 normally sends recursive queries. Recursion is automatically
514 when the <parameter>+nssearch</parameter> or
515 <parameter>+trace</parameter> query options are
522 <term><option>+[no]nssearch</option></term>
525 When this option is set, <command>dig</command>
527 authoritative name servers for the zone containing the name
529 looked up and display the SOA record that each name server has
537 <term><option>+[no]trace</option></term>
540 Toggle tracing of the delegation path from the root name servers
542 the name being looked up. Tracing is disabled by default. When
543 tracing is enabled, <command>dig</command> makes
545 resolve the name being looked up. It will follow referrals from
547 root servers, showing the answer from each server that was used
555 <term><option>+[no]cmd</option></term>
558 Toggles the printing of the initial comment in the output
560 the version of <command>dig</command> and the query
562 been applied. This comment is printed by default.
568 <term><option>+[no]short</option></term>
571 Provide a terse answer. The default is to print the answer in a
578 <term><option>+[no]identify</option></term>
581 Show [or do not show] the IP address and port number that
583 answer when the <parameter>+short</parameter> option
585 short form answers are requested, the default is not to show the
586 source address and port number of the server that provided the
593 <term><option>+[no]comments</option></term>
596 Toggle the display of comment lines in the output. The default
604 <term><option>+[no]stats</option></term>
607 This query option toggles the printing of statistics: when the
609 was made, the size of the reply and so on. The default
611 to print the query statistics.
617 <term><option>+[no]qr</option></term>
620 Print [do not print] the query as it is sent.
621 By default, the query is not printed.
627 <term><option>+[no]question</option></term>
630 Print [do not print] the question section of a query when an
632 returned. The default is to print the question section as a
639 <term><option>+[no]answer</option></term>
642 Display [do not display] the answer section of a reply. The
650 <term><option>+[no]authority</option></term>
653 Display [do not display] the authority section of a reply. The
654 default is to display it.
660 <term><option>+[no]additional</option></term>
663 Display [do not display] the additional section of a reply.
664 The default is to display it.
670 <term><option>+[no]all</option></term>
673 Set or clear all display flags.
679 <term><option>+time=T</option></term>
683 Sets the timeout for a query to
684 <parameter>T</parameter> seconds. The default
685 timeout is 5 seconds.
686 An attempt to set <parameter>T</parameter> to less
688 in a query timeout of 1 second being applied.
694 <term><option>+tries=T</option></term>
697 Sets the number of times to try UDP queries to server to
698 <parameter>T</parameter> instead of the default, 3.
700 <parameter>T</parameter> is less than or equal to
702 tries is silently rounded up to 1.
708 <term><option>+retry=T</option></term>
711 Sets the number of times to retry UDP queries to server to
712 <parameter>T</parameter> instead of the default, 2.
714 <parameter>+tries</parameter>, this does not include
722 <term><option>+ndots=D</option></term>
725 Set the number of dots that have to appear in
726 <parameter>name</parameter> to <parameter>D</parameter> for it to be
727 considered absolute. The default value is that defined using
729 ndots statement in <filename>/etc/resolv.conf</filename>, or 1 if no
730 ndots statement is present. Names with fewer dots are
732 relative names and will be searched for in the domains listed in
734 <option>search</option> or <option>domain</option> directive in
735 <filename>/etc/resolv.conf</filename>.
741 <term><option>+bufsize=B</option></term>
744 Set the UDP message buffer size advertised using EDNS0 to
745 <parameter>B</parameter> bytes. The maximum and minimum sizes
746 of this buffer are 65535 and 0 respectively. Values outside
747 this range are rounded up or down appropriately.
748 Values other than zero will cause a EDNS query to be sent.
754 <term><option>+edns=#</option></term>
757 Specify the EDNS version to query with. Valid values
758 are 0 to 255. Setting the EDNS version will cause a
759 EDNS query to be sent. <option>+noedns</option> clears the
760 remembered EDNS version.
766 <term><option>+[no]multiline</option></term>
769 Print records like the SOA records in a verbose multi-line
770 format with human-readable comments. The default is to print
771 each record on a single line, to facilitate machine parsing
772 of the <command>dig</command> output.
778 <term><option>+[no]onesoa</option></term>
781 Print only one (starting) SOA record when performing
782 an AXFR. The default is to print both the starting and
789 <term><option>+[no]fail</option></term>
792 Do not try the next server if you receive a SERVFAIL. The
794 to not try the next server which is the reverse of normal stub
802 <term><option>+[no]besteffort</option></term>
805 Attempt to display the contents of messages which are malformed.
806 The default is to not display malformed answers.
812 <term><option>+[no]dnssec</option></term>
815 Requests DNSSEC records be sent by setting the DNSSEC OK bit
817 in the OPT record in the additional section of the query.
823 <term><option>+[no]sigchase</option></term>
826 Chase DNSSEC signature chains. Requires dig be compiled with
833 <term><option>+trusted-key=####</option></term>
836 Specifies a file containing trusted keys to be used with
837 <option>+sigchase</option>. Each DNSKEY record must be
841 If not specified, <command>dig</command> will look for
842 <filename>/etc/trusted-key.key</filename> then
843 <filename>trusted-key.key</filename> in the current directory.
846 Requires dig be compiled with -DDIG_SIGCHASE.
852 <term><option>+[no]topdown</option></term>
855 When chasing DNSSEC signature chains perform a top-down
857 Requires dig be compiled with -DDIG_SIGCHASE.
863 <term><option>+[no]nsid</option></term>
866 Include an EDNS name server ID request when sending a query.
872 <term><option>+[no]keepopen</option></term>
875 Keep the TCP socket open between queries and reuse it rather
876 than creating a new TCP socket for each lookup. The default
877 is <option>+nokeepopen</option>.
888 <title>MULTIPLE QUERIES</title>
891 The BIND 9 implementation of <command>dig </command>
893 specifying multiple queries on the command line (in addition to
894 supporting the <option>-f</option> batch file option). Each of those
895 queries can be supplied with its own set of flags, options and query
900 In this case, each <parameter>query</parameter> argument
902 individual query in the command-line syntax described above. Each
903 consists of any of the standard options and flags, the name to be
904 looked up, an optional query type and class and any query options that
905 should be applied to that query.
909 A global set of query options, which should be applied to all queries,
910 can also be supplied. These global query options must precede the
911 first tuple of name, class, type, options, flags, and query options
912 supplied on the command line. Any global query options (except
913 the <option>+[no]cmd</option> option) can be
914 overridden by a query-specific set of query options. For example:
916 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
918 shows how <command>dig</command> could be used from the
920 to make three lookups: an ANY query for <literal>www.isc.org</literal>, a
921 reverse lookup of 127.0.0.1 and a query for the NS records of
922 <literal>isc.org</literal>.
924 A global query option of <parameter>+qr</parameter> is
926 that <command>dig</command> shows the initial query it made
928 lookup. The final query has a local query option of
929 <parameter>+noqr</parameter> which means that <command>dig</command>
930 will not print the initial query when it looks up the NS records for
931 <literal>isc.org</literal>.
937 <title>IDN SUPPORT</title>
939 If <command>dig</command> has been built with IDN (internationalized
940 domain name) support, it can accept and display non-ASCII domain names.
941 <command>dig</command> appropriately converts character encoding of
942 domain name before sending a request to DNS server or displaying a
943 reply from the server.
944 If you'd like to turn off the IDN support for some reason, defines
945 the <envar>IDN_DISABLE</envar> environment variable.
946 The IDN support is disabled if the variable is set when
947 <command>dig</command> runs.
953 <para><filename>/etc/resolv.conf</filename>
955 <para><filename>${HOME}/.digrc</filename>
960 <title>SEE ALSO</title>
962 <refentrytitle>host</refentrytitle><manvolnum>1</manvolnum>
965 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
968 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
970 <citetitle>RFC1035</citetitle>.
977 There are probably too many query options.