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21 <!-- $Id: dig.docbook,v 1.51 2011/11/04 11:02:50 jreed 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>
50 <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
57 <holder>Internet Software Consortium.</holder>
63 <command>dig</command>
64 <arg choice="opt">@server</arg>
65 <arg><option>-b <replaceable class="parameter">address</replaceable></option></arg>
66 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
67 <arg><option>-f <replaceable class="parameter">filename</replaceable></option></arg>
68 <arg><option>-k <replaceable class="parameter">filename</replaceable></option></arg>
69 <arg><option>-m</option></arg>
70 <arg><option>-p <replaceable class="parameter">port#</replaceable></option></arg>
71 <arg><option>-q <replaceable class="parameter">name</replaceable></option></arg>
72 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
73 <arg><option>-x <replaceable class="parameter">addr</replaceable></option></arg>
74 <arg><option>-y <replaceable class="parameter"><optional>hmac:</optional>name:key</replaceable></option></arg>
75 <arg><option>-4</option></arg>
76 <arg><option>-6</option></arg>
77 <arg choice="opt">name</arg>
78 <arg choice="opt">type</arg>
79 <arg choice="opt">class</arg>
80 <arg choice="opt" rep="repeat">queryopt</arg>
84 <command>dig</command>
85 <arg><option>-h</option></arg>
89 <command>dig</command>
90 <arg choice="opt" rep="repeat">global-queryopt</arg>
91 <arg choice="opt" rep="repeat">query</arg>
96 <title>DESCRIPTION</title>
97 <para><command>dig</command>
98 (domain information groper) is a flexible tool
99 for interrogating DNS name servers. It performs DNS lookups and
100 displays the answers that are returned from the name server(s) that
101 were queried. Most DNS administrators use <command>dig</command> to
102 troubleshoot DNS problems because of its flexibility, ease of use and
103 clarity of output. Other lookup tools tend to have less functionality
104 than <command>dig</command>.
108 Although <command>dig</command> is normally used with
110 arguments, it also has a batch mode of operation for reading lookup
111 requests from a file. A brief summary of its command-line arguments
112 and options is printed when the <option>-h</option> option is given.
113 Unlike earlier versions, the BIND 9 implementation of
114 <command>dig</command> allows multiple lookups to be issued
120 Unless it is told to query a specific name server,
121 <command>dig</command> will try each of the servers listed in
122 <filename>/etc/resolv.conf</filename>. If no usable server addresses
123 are found, <command>dig</command> will send the query to the local
128 When no command line arguments or options are given,
129 <command>dig</command> will perform an NS query for "." (the root).
133 It is possible to set per-user defaults for <command>dig</command> via
134 <filename>${HOME}/.digrc</filename>. This file is read and
136 are applied before the command line arguments.
140 The IN and CH class names overlap with the IN and CH top level
141 domains names. Either use the <option>-t</option> and
142 <option>-c</option> options to specify the type and class,
143 use the <option>-q</option> the specify the domain name, or
144 use "IN." and "CH." when looking up these top level domains.
150 <title>SIMPLE USAGE</title>
153 A typical invocation of <command>dig</command> looks like:
154 <programlisting> dig @server name type </programlisting>
160 <term><constant>server</constant></term>
163 is the name or IP address of the name server to query. This
164 can be an IPv4 address in dotted-decimal notation or an IPv6
165 address in colon-delimited notation. When the supplied
166 <parameter>server</parameter> argument is a hostname,
167 <command>dig</command> resolves that name before querying
171 If no <parameter>server</parameter> argument is
172 provided, <command>dig</command> consults
173 <filename>/etc/resolv.conf</filename>; if an
174 address is found there, it queries the name server at
175 that address. If either of the <option>-4</option> or
176 <option>-6</option> options are in use, then
177 only addresses for the corresponding transport
178 will be tried. If no usable addresses are found,
179 <command>dig</command> will send the query to the
180 local host. The reply from the name server that
181 responds is displayed.
187 <term><constant>name</constant></term>
190 is the name of the resource record that is to be looked up.
196 <term><constant>type</constant></term>
199 indicates what type of query is required —
200 ANY, A, MX, SIG, etc.
201 <parameter>type</parameter> can be any valid query
203 <parameter>type</parameter> argument is supplied,
204 <command>dig</command> will perform a lookup for an
216 <title>OPTIONS</title>
219 The <option>-b</option> option sets the source IP address of the query
220 to <parameter>address</parameter>. This must be a valid
222 one of the host's network interfaces or "0.0.0.0" or "::". An optional
224 may be specified by appending "#<port>"
228 The default query class (IN for internet) is overridden by the
229 <option>-c</option> option. <parameter>class</parameter> is
231 class, such as HS for Hesiod records or CH for Chaosnet records.
235 The <option>-f</option> option makes <command>dig </command>
237 in batch mode by reading a list of lookup requests to process from the
238 file <parameter>filename</parameter>. The file contains a
240 queries, one per line. Each entry in the file should be organized in
241 the same way they would be presented as queries to
242 <command>dig</command> using the command-line interface.
246 The <option>-m</option> option enables memory usage debugging.
247 <!-- It enables ISC_MEM_DEBUGTRACE and ISC_MEM_DEBUGRECORD
248 documented in include/isc/mem.h -->
252 If a non-standard port number is to be queried, the
253 <option>-p</option> option is used. <parameter>port#</parameter> is
254 the port number that <command>dig</command> will send its
256 instead of the standard DNS port number 53. This option would be used
257 to test a name server that has been configured to listen for queries
258 on a non-standard port number.
262 The <option>-4</option> option forces <command>dig</command>
264 use IPv4 query transport. The <option>-6</option> option forces
265 <command>dig</command> to only use IPv6 query transport.
269 The <option>-t</option> option sets the query type to
270 <parameter>type</parameter>. It can be any valid query type
272 supported in BIND 9. The default query type is "A", unless the
273 <option>-x</option> option is supplied to indicate a reverse lookup.
274 A zone transfer can be requested by specifying a type of AXFR. When
275 an incremental zone transfer (IXFR) is required,
276 <parameter>type</parameter> is set to <literal>ixfr=N</literal>.
277 The incremental zone transfer will contain the changes made to the zone
278 since the serial number in the zone's SOA record was
279 <parameter>N</parameter>.
283 The <option>-q</option> option sets the query name to
284 <parameter>name</parameter>. This useful do distinguish the
285 <parameter>name</parameter> from other arguments.
289 Reverse lookups — mapping addresses to names — are simplified by the
290 <option>-x</option> option. <parameter>addr</parameter> is
292 address in dotted-decimal notation, or a colon-delimited IPv6 address.
293 When this option is used, there is no need to provide the
294 <parameter>name</parameter>, <parameter>class</parameter> and
295 <parameter>type</parameter> arguments. <command>dig</command>
296 automatically performs a lookup for a name like
297 <literal>11.12.13.10.in-addr.arpa</literal> and sets the
299 class to PTR and IN respectively. By default, IPv6 addresses are
300 looked up using nibble format under the IP6.ARPA domain.
301 To use the older RFC1886 method using the IP6.INT domain
302 specify the <option>-i</option> option. Bit string labels (RFC2874)
303 are now experimental and are not attempted.
307 To sign the DNS queries sent by <command>dig</command> and
309 responses using transaction signatures (TSIG), specify a TSIG key file
310 using the <option>-k</option> option. You can also specify the TSIG
311 key itself on the command line using the <option>-y</option> option;
312 <parameter>hmac</parameter> is the type of the TSIG, default HMAC-MD5,
313 <parameter>name</parameter> is the name of the TSIG key and
314 <parameter>key</parameter> is the actual key. The key is a
316 encoded string, typically generated by
318 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
321 Caution should be taken when using the <option>-y</option> option on
322 multi-user systems as the key can be visible in the output from
324 <refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum>
326 or in the shell's history file. When
327 using TSIG authentication with <command>dig</command>, the name
328 server that is queried needs to know the key and algorithm that is
329 being used. In BIND, this is done by providing appropriate
330 <command>key</command> and <command>server</command> statements in
331 <filename>named.conf</filename>.
337 <title>QUERY OPTIONS</title>
339 <para><command>dig</command>
340 provides a number of query options which affect
341 the way in which lookups are made and the results displayed. Some of
342 these set or reset flag bits in the query header, some determine which
343 sections of the answer get printed, and others determine the timeout
344 and retry strategies.
348 Each query option is identified by a keyword preceded by a plus sign
349 (<literal>+</literal>). Some keywords set or reset an
350 option. These may be preceded
351 by the string <literal>no</literal> to negate the meaning of
353 keywords assign values to options like the timeout interval. They
354 have the form <option>+keyword=value</option>.
355 The query options are:
360 <term><option>+[no]tcp</option></term>
363 Use [do not use] TCP when querying name servers. The default
364 behavior is to use UDP unless an AXFR or IXFR query is
366 which case a TCP connection is used.
372 <term><option>+[no]vc</option></term>
375 Use [do not use] TCP when querying name servers. This alternate
376 syntax to <parameter>+[no]tcp</parameter> is
377 provided for backwards
378 compatibility. The "vc" stands for "virtual circuit".
384 <term><option>+[no]ignore</option></term>
387 Ignore truncation in UDP responses instead of retrying with TCP.
389 default, TCP retries are performed.
395 <term><option>+domain=somename</option></term>
398 Set the search list to contain the single domain
399 <parameter>somename</parameter>, as if specified in
401 <command>domain</command> directive in
402 <filename>/etc/resolv.conf</filename>, and enable
404 processing as if the <parameter>+search</parameter>
411 <term><option>+[no]search</option></term>
414 Use [do not use] the search list defined by the searchlist or
416 directive in <filename>resolv.conf</filename> (if
418 The search list is not used by default.
424 <term><option>+[no]showsearch</option></term>
427 Perform [do not perform] a search showing intermediate
434 <term><option>+[no]defname</option></term>
437 Deprecated, treated as a synonym for <parameter>+[no]search</parameter>
443 <term><option>+[no]aaonly</option></term>
446 Sets the "aa" flag in the query.
452 <term><option>+[no]aaflag</option></term>
455 A synonym for <parameter>+[no]aaonly</parameter>.
461 <term><option>+[no]adflag</option></term>
464 Set [do not set] the AD (authentic data) bit in the
465 query. This requests the server to return whether
466 all of the answer and authority sections have all
467 been validated as secure according to the security
468 policy of the server. AD=1 indicates that all records
469 have been validated as secure and the answer is not
470 from a OPT-OUT range. AD=0 indicate that some part
471 of the answer was insecure or not validated. This
472 bit is set by default.
478 <term><option>+[no]cdflag</option></term>
481 Set [do not set] the CD (checking disabled) bit in the query.
483 requests the server to not perform DNSSEC validation of
490 <term><option>+[no]cl</option></term>
493 Display [do not display] the CLASS when printing the record.
499 <term><option>+[no]ttlid</option></term>
502 Display [do not display] the TTL when printing the record.
508 <term><option>+[no]recurse</option></term>
511 Toggle the setting of the RD (recursion desired) bit
512 in the query. This bit is set by default, which means
513 <command>dig</command> normally sends recursive
514 queries. Recursion is automatically disabled when
515 the <parameter>+nssearch</parameter> or
516 <parameter>+trace</parameter> query options are used.
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
541 name servers for the name being looked up. Tracing
542 is disabled by default. When tracing is enabled,
543 <command>dig</command> makes iterative queries to
544 resolve the name being looked up. It will follow
545 referrals from the root servers, showing the answer
546 from each server that was used to resolve the lookup.
549 <command>+dnssec</command> is also set when +trace is
550 set to better emulate the default queries from a nameserver.
556 <term><option>+[no]cmd</option></term>
559 Toggles the printing of the initial comment in the output
561 the version of <command>dig</command> and the query
563 been applied. This comment is printed by default.
569 <term><option>+[no]short</option></term>
572 Provide a terse answer. The default is to print the answer in a
579 <term><option>+[no]identify</option></term>
582 Show [or do not show] the IP address and port number that
584 answer when the <parameter>+short</parameter> option
586 short form answers are requested, the default is not to show the
587 source address and port number of the server that provided the
594 <term><option>+[no]comments</option></term>
597 Toggle the display of comment lines in the output. The default
598 is to print comments.
604 <term><option>+[no]rrcomments</option></term>
607 Toggle the display of per-record comments in the output (for
608 example, human-readable key information about DNSKEY records).
609 The default is not to print record comments unless multiline
616 <term><option>+split=W</option></term>
619 Split long hex- or base64-formatted fields in resource
620 records into chunks of <parameter>W</parameter> characters
621 (where <parameter>W</parameter> is rounded up to the nearest
623 <parameter>+nosplit</parameter> or
624 <parameter>+split=0</parameter> causes fields not to be
625 split at all. The default is 56 characters, or 44 characters
626 when multiline mode is active.
632 <term><option>+[no]stats</option></term>
635 This query option toggles the printing of statistics: when the
637 was made, the size of the reply and so on. The default
639 to print the query statistics.
645 <term><option>+[no]qr</option></term>
648 Print [do not print] the query as it is sent.
649 By default, the query is not printed.
655 <term><option>+[no]question</option></term>
658 Print [do not print] the question section of a query when an
660 returned. The default is to print the question section as a
667 <term><option>+[no]answer</option></term>
670 Display [do not display] the answer section of a reply. The
678 <term><option>+[no]authority</option></term>
681 Display [do not display] the authority section of a reply. The
682 default is to display it.
688 <term><option>+[no]additional</option></term>
691 Display [do not display] the additional section of a reply.
692 The default is to display it.
698 <term><option>+[no]all</option></term>
701 Set or clear all display flags.
707 <term><option>+time=T</option></term>
711 Sets the timeout for a query to
712 <parameter>T</parameter> seconds. The default
713 timeout is 5 seconds.
714 An attempt to set <parameter>T</parameter> to less
716 in a query timeout of 1 second being applied.
722 <term><option>+tries=T</option></term>
725 Sets the number of times to try UDP queries to server to
726 <parameter>T</parameter> instead of the default, 3.
728 <parameter>T</parameter> is less than or equal to
730 tries is silently rounded up to 1.
736 <term><option>+retry=T</option></term>
739 Sets the number of times to retry UDP queries to server to
740 <parameter>T</parameter> instead of the default, 2.
742 <parameter>+tries</parameter>, this does not include
750 <term><option>+ndots=D</option></term>
753 Set the number of dots that have to appear in
754 <parameter>name</parameter> to <parameter>D</parameter> for it to be
755 considered absolute. The default value is that defined using
757 ndots statement in <filename>/etc/resolv.conf</filename>, or 1 if no
758 ndots statement is present. Names with fewer dots are
760 relative names and will be searched for in the domains listed in
762 <option>search</option> or <option>domain</option> directive in
763 <filename>/etc/resolv.conf</filename>.
769 <term><option>+bufsize=B</option></term>
772 Set the UDP message buffer size advertised using EDNS0 to
773 <parameter>B</parameter> bytes. The maximum and minimum sizes
774 of this buffer are 65535 and 0 respectively. Values outside
775 this range are rounded up or down appropriately.
776 Values other than zero will cause a EDNS query to be sent.
782 <term><option>+edns=#</option></term>
785 Specify the EDNS version to query with. Valid values
786 are 0 to 255. Setting the EDNS version will cause
787 a EDNS query to be sent. <option>+noedns</option>
788 clears the remembered EDNS version. EDNS is set to
795 <term><option>+[no]multiline</option></term>
798 Print records like the SOA records in a verbose multi-line
799 format with human-readable comments. The default is to print
800 each record on a single line, to facilitate machine parsing
801 of the <command>dig</command> output.
807 <term><option>+[no]onesoa</option></term>
810 Print only one (starting) SOA record when performing
811 an AXFR. The default is to print both the starting and
818 <term><option>+[no]fail</option></term>
821 Do not try the next server if you receive a SERVFAIL. The
823 to not try the next server which is the reverse of normal stub
831 <term><option>+[no]besteffort</option></term>
834 Attempt to display the contents of messages which are malformed.
835 The default is to not display malformed answers.
841 <term><option>+[no]dnssec</option></term>
844 Requests DNSSEC records be sent by setting the DNSSEC OK bit
846 in the OPT record in the additional section of the query.
852 <term><option>+[no]sigchase</option></term>
855 Chase DNSSEC signature chains. Requires dig be compiled with
862 <term><option>+trusted-key=####</option></term>
865 Specifies a file containing trusted keys to be used with
866 <option>+sigchase</option>. Each DNSKEY record must be
870 If not specified, <command>dig</command> will look for
871 <filename>/etc/trusted-key.key</filename> then
872 <filename>trusted-key.key</filename> in the current directory.
875 Requires dig be compiled with -DDIG_SIGCHASE.
881 <term><option>+[no]topdown</option></term>
884 When chasing DNSSEC signature chains perform a top-down
886 Requires dig be compiled with -DDIG_SIGCHASE.
892 <term><option>+[no]nsid</option></term>
895 Include an EDNS name server ID request when sending a query.
901 <term><option>+[no]keepopen</option></term>
904 Keep the TCP socket open between queries and reuse it rather
905 than creating a new TCP socket for each lookup. The default
906 is <option>+nokeepopen</option>.
917 <title>MULTIPLE QUERIES</title>
920 The BIND 9 implementation of <command>dig </command>
922 specifying multiple queries on the command line (in addition to
923 supporting the <option>-f</option> batch file option). Each of those
924 queries can be supplied with its own set of flags, options and query
929 In this case, each <parameter>query</parameter> argument
931 individual query in the command-line syntax described above. Each
932 consists of any of the standard options and flags, the name to be
933 looked up, an optional query type and class and any query options that
934 should be applied to that query.
938 A global set of query options, which should be applied to all queries,
939 can also be supplied. These global query options must precede the
940 first tuple of name, class, type, options, flags, and query options
941 supplied on the command line. Any global query options (except
942 the <option>+[no]cmd</option> option) can be
943 overridden by a query-specific set of query options. For example:
945 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
947 shows how <command>dig</command> could be used from the
949 to make three lookups: an ANY query for <literal>www.isc.org</literal>, a
950 reverse lookup of 127.0.0.1 and a query for the NS records of
951 <literal>isc.org</literal>.
953 A global query option of <parameter>+qr</parameter> is
955 that <command>dig</command> shows the initial query it made
957 lookup. The final query has a local query option of
958 <parameter>+noqr</parameter> which means that <command>dig</command>
959 will not print the initial query when it looks up the NS records for
960 <literal>isc.org</literal>.
966 <title>IDN SUPPORT</title>
968 If <command>dig</command> has been built with IDN (internationalized
969 domain name) support, it can accept and display non-ASCII domain names.
970 <command>dig</command> appropriately converts character encoding of
971 domain name before sending a request to DNS server or displaying a
972 reply from the server.
973 If you'd like to turn off the IDN support for some reason, defines
974 the <envar>IDN_DISABLE</envar> environment variable.
975 The IDN support is disabled if the variable is set when
976 <command>dig</command> runs.
982 <para><filename>/etc/resolv.conf</filename>
984 <para><filename>${HOME}/.digrc</filename>
989 <title>SEE ALSO</title>
991 <refentrytitle>host</refentrytitle><manvolnum>1</manvolnum>
994 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
997 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
999 <citetitle>RFC1035</citetitle>.
1006 There are probably too many query options.