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21 <!-- $Id: dig.docbook,v 1.47 2010/03/04 23:50:34 tbox Exp $ -->
22 <refentry id="man.dig">
25 <date>Jun 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>
48 <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
55 <holder>Internet Software Consortium.</holder>
61 <command>dig</command>
62 <arg choice="opt">@server</arg>
63 <arg><option>-b <replaceable class="parameter">address</replaceable></option></arg>
64 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
65 <arg><option>-f <replaceable class="parameter">filename</replaceable></option></arg>
66 <arg><option>-k <replaceable class="parameter">filename</replaceable></option></arg>
67 <arg><option>-m</option></arg>
68 <arg><option>-p <replaceable class="parameter">port#</replaceable></option></arg>
69 <arg><option>-q <replaceable class="parameter">name</replaceable></option></arg>
70 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
71 <arg><option>-x <replaceable class="parameter">addr</replaceable></option></arg>
72 <arg><option>-y <replaceable class="parameter"><optional>hmac:</optional>name:key</replaceable></option></arg>
73 <arg><option>-4</option></arg>
74 <arg><option>-6</option></arg>
75 <arg choice="opt">name</arg>
76 <arg choice="opt">type</arg>
77 <arg choice="opt">class</arg>
78 <arg choice="opt" rep="repeat">queryopt</arg>
82 <command>dig</command>
83 <arg><option>-h</option></arg>
87 <command>dig</command>
88 <arg choice="opt" rep="repeat">global-queryopt</arg>
89 <arg choice="opt" rep="repeat">query</arg>
94 <title>DESCRIPTION</title>
95 <para><command>dig</command>
96 (domain information groper) is a flexible tool
97 for interrogating DNS name servers. It performs DNS lookups and
98 displays the answers that are returned from the name server(s) that
99 were queried. Most DNS administrators use <command>dig</command> to
100 troubleshoot DNS problems because of its flexibility, ease of use and
101 clarity of output. Other lookup tools tend to have less functionality
102 than <command>dig</command>.
106 Although <command>dig</command> is normally used with
108 arguments, it also has a batch mode of operation for reading lookup
109 requests from a file. A brief summary of its command-line arguments
110 and options is printed when the <option>-h</option> option is given.
111 Unlike earlier versions, the BIND 9 implementation of
112 <command>dig</command> allows multiple lookups to be issued
118 Unless it is told to query a specific name server,
119 <command>dig</command> will try each of the servers listed
121 <filename>/etc/resolv.conf</filename>.
125 When no command line arguments or options are given,
126 <command>dig</command> will perform an NS query for "." (the root).
130 It is possible to set per-user defaults for <command>dig</command> via
131 <filename>${HOME}/.digrc</filename>. This file is read and
133 are applied before the command line arguments.
137 The IN and CH class names overlap with the IN and CH top level
138 domains names. Either use the <option>-t</option> and
139 <option>-c</option> options to specify the type and class,
140 use the <option>-q</option> the specify the domain name, or
141 use "IN." and "CH." when looking up these top level domains.
147 <title>SIMPLE USAGE</title>
150 A typical invocation of <command>dig</command> looks like:
151 <programlisting> dig @server name type </programlisting>
157 <term><constant>server</constant></term>
160 is the name or IP address of the name server to query. This can
162 address in dotted-decimal notation or an IPv6
163 address in colon-delimited notation. When the supplied
164 <parameter>server</parameter> argument is a
166 <command>dig</command> resolves that name before
168 server. If no <parameter>server</parameter>
169 argument is provided,
170 <command>dig</command> consults <filename>/etc/resolv.conf</filename>
171 and queries the name servers listed there. The reply from the
173 server that responds is displayed.
179 <term><constant>name</constant></term>
182 is the name of the resource record that is to be looked up.
188 <term><constant>type</constant></term>
191 indicates what type of query is required —
192 ANY, A, MX, SIG, etc.
193 <parameter>type</parameter> can be any valid query
195 <parameter>type</parameter> argument is supplied,
196 <command>dig</command> will perform a lookup for an
208 <title>OPTIONS</title>
211 The <option>-b</option> option sets the source IP address of the query
212 to <parameter>address</parameter>. This must be a valid
214 one of the host's network interfaces or "0.0.0.0" or "::". An optional
216 may be specified by appending "#<port>"
220 The default query class (IN for internet) is overridden by the
221 <option>-c</option> option. <parameter>class</parameter> is
223 class, such as HS for Hesiod records or CH for Chaosnet records.
227 The <option>-f</option> option makes <command>dig </command>
229 in batch mode by reading a list of lookup requests to process from the
230 file <parameter>filename</parameter>. The file contains a
232 queries, one per line. Each entry in the file should be organized in
233 the same way they would be presented as queries to
234 <command>dig</command> using the command-line interface.
238 The <option>-m</option> option enables memory usage debugging.
239 <!-- It enables ISC_MEM_DEBUGTRACE and ISC_MEM_DEBUGRECORD
240 documented in include/isc/mem.h -->
244 If a non-standard port number is to be queried, the
245 <option>-p</option> option is used. <parameter>port#</parameter> is
246 the port number that <command>dig</command> will send its
248 instead of the standard DNS port number 53. This option would be used
249 to test a name server that has been configured to listen for queries
250 on a non-standard port number.
254 The <option>-4</option> option forces <command>dig</command>
256 use IPv4 query transport. The <option>-6</option> option forces
257 <command>dig</command> to only use IPv6 query transport.
261 The <option>-t</option> option sets the query type to
262 <parameter>type</parameter>. It can be any valid query type
264 supported in BIND 9. The default query type is "A", unless the
265 <option>-x</option> option is supplied to indicate a reverse lookup.
266 A zone transfer can be requested by specifying a type of AXFR. When
267 an incremental zone transfer (IXFR) is required,
268 <parameter>type</parameter> is set to <literal>ixfr=N</literal>.
269 The incremental zone transfer will contain the changes made to the zone
270 since the serial number in the zone's SOA record was
271 <parameter>N</parameter>.
275 The <option>-q</option> option sets the query name to
276 <parameter>name</parameter>. This useful do distinguish the
277 <parameter>name</parameter> from other arguments.
281 Reverse lookups — mapping addresses to names — are simplified by the
282 <option>-x</option> option. <parameter>addr</parameter> is
284 address in dotted-decimal notation, or a colon-delimited IPv6 address.
285 When this option is used, there is no need to provide the
286 <parameter>name</parameter>, <parameter>class</parameter> and
287 <parameter>type</parameter> arguments. <command>dig</command>
288 automatically performs a lookup for a name like
289 <literal>11.12.13.10.in-addr.arpa</literal> and sets the
291 class to PTR and IN respectively. By default, IPv6 addresses are
292 looked up using nibble format under the IP6.ARPA domain.
293 To use the older RFC1886 method using the IP6.INT domain
294 specify the <option>-i</option> option. Bit string labels (RFC2874)
295 are now experimental and are not attempted.
299 To sign the DNS queries sent by <command>dig</command> and
301 responses using transaction signatures (TSIG), specify a TSIG key file
302 using the <option>-k</option> option. You can also specify the TSIG
303 key itself on the command line using the <option>-y</option> option;
304 <parameter>hmac</parameter> is the type of the TSIG, default HMAC-MD5,
305 <parameter>name</parameter> is the name of the TSIG key and
306 <parameter>key</parameter> is the actual key. The key is a
308 encoded string, typically generated by
310 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
313 Caution should be taken when using the <option>-y</option> option on
314 multi-user systems as the key can be visible in the output from
316 <refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum>
318 or in the shell's history file. When
319 using TSIG authentication with <command>dig</command>, the name
320 server that is queried needs to know the key and algorithm that is
321 being used. In BIND, this is done by providing appropriate
322 <command>key</command> and <command>server</command> statements in
323 <filename>named.conf</filename>.
329 <title>QUERY OPTIONS</title>
331 <para><command>dig</command>
332 provides a number of query options which affect
333 the way in which lookups are made and the results displayed. Some of
334 these set or reset flag bits in the query header, some determine which
335 sections of the answer get printed, and others determine the timeout
336 and retry strategies.
340 Each query option is identified by a keyword preceded by a plus sign
341 (<literal>+</literal>). Some keywords set or reset an
342 option. These may be preceded
343 by the string <literal>no</literal> to negate the meaning of
345 keywords assign values to options like the timeout interval. They
346 have the form <option>+keyword=value</option>.
347 The query options are:
352 <term><option>+[no]tcp</option></term>
355 Use [do not use] TCP when querying name servers. The default
356 behavior is to use UDP unless an AXFR or IXFR query is
358 which case a TCP connection is used.
364 <term><option>+[no]vc</option></term>
367 Use [do not use] TCP when querying name servers. This alternate
368 syntax to <parameter>+[no]tcp</parameter> is
369 provided for backwards
370 compatibility. The "vc" stands for "virtual circuit".
376 <term><option>+[no]ignore</option></term>
379 Ignore truncation in UDP responses instead of retrying with TCP.
381 default, TCP retries are performed.
387 <term><option>+domain=somename</option></term>
390 Set the search list to contain the single domain
391 <parameter>somename</parameter>, as if specified in
393 <command>domain</command> directive in
394 <filename>/etc/resolv.conf</filename>, and enable
396 processing as if the <parameter>+search</parameter>
403 <term><option>+[no]search</option></term>
406 Use [do not use] the search list defined by the searchlist or
408 directive in <filename>resolv.conf</filename> (if
410 The search list is not used by default.
416 <term><option>+[no]showsearch</option></term>
419 Perform [do not perform] a search showing intermediate
426 <term><option>+[no]defname</option></term>
429 Deprecated, treated as a synonym for <parameter>+[no]search</parameter>
435 <term><option>+[no]aaonly</option></term>
438 Sets the "aa" flag in the query.
444 <term><option>+[no]aaflag</option></term>
447 A synonym for <parameter>+[no]aaonly</parameter>.
453 <term><option>+[no]adflag</option></term>
456 Set [do not set] the AD (authentic data) bit in the
457 query. This requests the server to return whether
458 all of the answer and authority sections have all
459 been validated as secure according to the security
460 policy of the server. AD=1 indicates that all records
461 have been validated as secure and the answer is not
462 from a OPT-OUT range. AD=0 indicate that some part
463 of the answer was insecure or not validated.
469 <term><option>+[no]cdflag</option></term>
472 Set [do not set] the CD (checking disabled) bit in the query.
474 requests the server to not perform DNSSEC validation of
481 <term><option>+[no]cl</option></term>
484 Display [do not display] the CLASS when printing the record.
490 <term><option>+[no]ttlid</option></term>
493 Display [do not display] the TTL when printing the record.
499 <term><option>+[no]recurse</option></term>
502 Toggle the setting of the RD (recursion desired) bit in the
504 This bit is set by default, which means <command>dig</command>
505 normally sends recursive queries. Recursion is automatically
507 when the <parameter>+nssearch</parameter> or
508 <parameter>+trace</parameter> query options are
515 <term><option>+[no]nssearch</option></term>
518 When this option is set, <command>dig</command>
520 authoritative name servers for the zone containing the name
522 looked up and display the SOA record that each name server has
530 <term><option>+[no]trace</option></term>
533 Toggle tracing of the delegation path from the root name servers
535 the name being looked up. Tracing is disabled by default. When
536 tracing is enabled, <command>dig</command> makes
538 resolve the name being looked up. It will follow referrals from
540 root servers, showing the answer from each server that was used
548 <term><option>+[no]cmd</option></term>
551 Toggles the printing of the initial comment in the output
553 the version of <command>dig</command> and the query
555 been applied. This comment is printed by default.
561 <term><option>+[no]short</option></term>
564 Provide a terse answer. The default is to print the answer in a
571 <term><option>+[no]identify</option></term>
574 Show [or do not show] the IP address and port number that
576 answer when the <parameter>+short</parameter> option
578 short form answers are requested, the default is not to show the
579 source address and port number of the server that provided the
586 <term><option>+[no]comments</option></term>
589 Toggle the display of comment lines in the output. The default
597 <term><option>+[no]stats</option></term>
600 This query option toggles the printing of statistics: when the
602 was made, the size of the reply and so on. The default
604 to print the query statistics.
610 <term><option>+[no]qr</option></term>
613 Print [do not print] the query as it is sent.
614 By default, the query is not printed.
620 <term><option>+[no]question</option></term>
623 Print [do not print] the question section of a query when an
625 returned. The default is to print the question section as a
632 <term><option>+[no]answer</option></term>
635 Display [do not display] the answer section of a reply. The
643 <term><option>+[no]authority</option></term>
646 Display [do not display] the authority section of a reply. The
647 default is to display it.
653 <term><option>+[no]additional</option></term>
656 Display [do not display] the additional section of a reply.
657 The default is to display it.
663 <term><option>+[no]all</option></term>
666 Set or clear all display flags.
672 <term><option>+time=T</option></term>
676 Sets the timeout for a query to
677 <parameter>T</parameter> seconds. The default
678 timeout is 5 seconds.
679 An attempt to set <parameter>T</parameter> to less
681 in a query timeout of 1 second being applied.
687 <term><option>+tries=T</option></term>
690 Sets the number of times to try UDP queries to server to
691 <parameter>T</parameter> instead of the default, 3.
693 <parameter>T</parameter> is less than or equal to
695 tries is silently rounded up to 1.
701 <term><option>+retry=T</option></term>
704 Sets the number of times to retry UDP queries to server to
705 <parameter>T</parameter> instead of the default, 2.
707 <parameter>+tries</parameter>, this does not include
715 <term><option>+ndots=D</option></term>
718 Set the number of dots that have to appear in
719 <parameter>name</parameter> to <parameter>D</parameter> for it to be
720 considered absolute. The default value is that defined using
722 ndots statement in <filename>/etc/resolv.conf</filename>, or 1 if no
723 ndots statement is present. Names with fewer dots are
725 relative names and will be searched for in the domains listed in
727 <option>search</option> or <option>domain</option> directive in
728 <filename>/etc/resolv.conf</filename>.
734 <term><option>+bufsize=B</option></term>
737 Set the UDP message buffer size advertised using EDNS0 to
738 <parameter>B</parameter> bytes. The maximum and minimum sizes
739 of this buffer are 65535 and 0 respectively. Values outside
740 this range are rounded up or down appropriately.
741 Values other than zero will cause a EDNS query to be sent.
747 <term><option>+edns=#</option></term>
750 Specify the EDNS version to query with. Valid values
751 are 0 to 255. Setting the EDNS version will cause a
752 EDNS query to be sent. <option>+noedns</option> clears the
753 remembered EDNS version.
759 <term><option>+[no]multiline</option></term>
762 Print records like the SOA records in a verbose multi-line
763 format with human-readable comments. The default is to print
764 each record on a single line, to facilitate machine parsing
765 of the <command>dig</command> output.
771 <term><option>+[no]onesoa</option></term>
774 Print only one (starting) SOA record when performing
775 an AXFR. The default is to print both the starting and
782 <term><option>+[no]fail</option></term>
785 Do not try the next server if you receive a SERVFAIL. The
787 to not try the next server which is the reverse of normal stub
795 <term><option>+[no]besteffort</option></term>
798 Attempt to display the contents of messages which are malformed.
799 The default is to not display malformed answers.
805 <term><option>+[no]dnssec</option></term>
808 Requests DNSSEC records be sent by setting the DNSSEC OK bit
810 in the OPT record in the additional section of the query.
816 <term><option>+[no]sigchase</option></term>
819 Chase DNSSEC signature chains. Requires dig be compiled with
826 <term><option>+trusted-key=####</option></term>
829 Specifies a file containing trusted keys to be used with
830 <option>+sigchase</option>. Each DNSKEY record must be
834 If not specified, <command>dig</command> will look for
835 <filename>/etc/trusted-key.key</filename> then
836 <filename>trusted-key.key</filename> in the current directory.
839 Requires dig be compiled with -DDIG_SIGCHASE.
845 <term><option>+[no]topdown</option></term>
848 When chasing DNSSEC signature chains perform a top-down
850 Requires dig be compiled with -DDIG_SIGCHASE.
856 <term><option>+[no]nsid</option></term>
859 Include an EDNS name server ID request when sending a query.
871 <title>MULTIPLE QUERIES</title>
874 The BIND 9 implementation of <command>dig </command>
876 specifying multiple queries on the command line (in addition to
877 supporting the <option>-f</option> batch file option). Each of those
878 queries can be supplied with its own set of flags, options and query
883 In this case, each <parameter>query</parameter> argument
885 individual query in the command-line syntax described above. Each
886 consists of any of the standard options and flags, the name to be
887 looked up, an optional query type and class and any query options that
888 should be applied to that query.
892 A global set of query options, which should be applied to all queries,
893 can also be supplied. These global query options must precede the
894 first tuple of name, class, type, options, flags, and query options
895 supplied on the command line. Any global query options (except
896 the <option>+[no]cmd</option> option) can be
897 overridden by a query-specific set of query options. For example:
899 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
901 shows how <command>dig</command> could be used from the
903 to make three lookups: an ANY query for <literal>www.isc.org</literal>, a
904 reverse lookup of 127.0.0.1 and a query for the NS records of
905 <literal>isc.org</literal>.
907 A global query option of <parameter>+qr</parameter> is
909 that <command>dig</command> shows the initial query it made
911 lookup. The final query has a local query option of
912 <parameter>+noqr</parameter> which means that <command>dig</command>
913 will not print the initial query when it looks up the NS records for
914 <literal>isc.org</literal>.
920 <title>IDN SUPPORT</title>
922 If <command>dig</command> has been built with IDN (internationalized
923 domain name) support, it can accept and display non-ASCII domain names.
924 <command>dig</command> appropriately converts character encoding of
925 domain name before sending a request to DNS server or displaying a
926 reply from the server.
927 If you'd like to turn off the IDN support for some reason, defines
928 the <envar>IDN_DISABLE</envar> environment variable.
929 The IDN support is disabled if the variable is set when
930 <command>dig</command> runs.
936 <para><filename>/etc/resolv.conf</filename>
938 <para><filename>${HOME}/.digrc</filename>
943 <title>SEE ALSO</title>
945 <refentrytitle>host</refentrytitle><manvolnum>1</manvolnum>
948 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
951 <refentrytitle>dnssec-keygen</refentrytitle><manvolnum>8</manvolnum>
953 <citetitle>RFC1035</citetitle>.
960 There are probably too many query options.