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42 <div class="refentry" lang="en">
43 <a name="man.dig"></a><div class="titlepage"></div>
44 <div class="refnamediv">
46 <p>dig — DNS lookup utility</p>
48 <div class="refsynopsisdiv">
50 <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">-q <em class="replaceable"><code>name</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>[<span class="optional">hmac:</span>]name:key</code></em></code>] [<code class="option">-4</code>] [<code class="option">-6</code>] [name] [type] [class] [queryopt...]</p></div>
51 <div class="cmdsynopsis"><p><code class="command">dig</code> [<code class="option">-h</code>]</p></div>
52 <div class="cmdsynopsis"><p><code class="command">dig</code> [global-queryopt...] [query...]</p></div>
54 <div class="refsect1" lang="en">
55 <a name="id2564009"></a><h2>DESCRIPTION</h2>
56 <p><span><strong class="command">dig</strong></span>
57 (domain information groper) is a flexible tool
58 for interrogating DNS name servers. It performs DNS lookups and
59 displays the answers that are returned from the name server(s) that
60 were queried. Most DNS administrators use <span><strong class="command">dig</strong></span> to
61 troubleshoot DNS problems because of its flexibility, ease of use and
62 clarity of output. Other lookup tools tend to have less functionality
63 than <span><strong class="command">dig</strong></span>.
66 Although <span><strong class="command">dig</strong></span> is normally used with
68 arguments, it also has a batch mode of operation for reading lookup
69 requests from a file. A brief summary of its command-line arguments
70 and options is printed when the <code class="option">-h</code> option is given.
71 Unlike earlier versions, the BIND9 implementation of
72 <span><strong class="command">dig</strong></span> allows multiple lookups to be issued
77 Unless it is told to query a specific name server,
78 <span><strong class="command">dig</strong></span> will try each of the servers listed
80 <code class="filename">/etc/resolv.conf</code>.
83 When no command line arguments or options are given, will perform an
84 NS query for "." (the root).
87 It is possible to set per-user defaults for <span><strong class="command">dig</strong></span> via
88 <code class="filename">${HOME}/.digrc</code>. This file is read and
90 are applied before the command line arguments.
93 The IN and CH class names overlap with the IN and CH top level
94 domains names. Either use the <code class="option">-t</code> and
95 <code class="option">-c</code> options to specify the type and class or
96 use the <code class="option">-q</code> the specify the domain name or
97 use "IN." and "CH." when looking up these top level domains.
100 <div class="refsect1" lang="en">
101 <a name="id2572153"></a><h2>SIMPLE USAGE</h2>
103 A typical invocation of <span><strong class="command">dig</strong></span> looks like:
105 <pre class="programlisting"> dig @server name type </pre>
110 <div class="variablelist"><dl>
111 <dt><span class="term"><code class="constant">server</code></span></dt>
113 is the name or IP address of the name server to query. This can
115 address in dotted-decimal notation or an IPv6
116 address in colon-delimited notation. When the supplied
117 <em class="parameter"><code>server</code></em> argument is a
119 <span><strong class="command">dig</strong></span> resolves that name before
121 server. If no <em class="parameter"><code>server</code></em>
122 argument is provided,
123 <span><strong class="command">dig</strong></span> consults <code class="filename">/etc/resolv.conf</code>
124 and queries the name servers listed there. The reply from the
126 server that responds is displayed.
128 <dt><span class="term"><code class="constant">name</code></span></dt>
130 is the name of the resource record that is to be looked up.
132 <dt><span class="term"><code class="constant">type</code></span></dt>
134 indicates what type of query is required —
135 ANY, A, MX, SIG, etc.
136 <em class="parameter"><code>type</code></em> can be any valid query
138 <em class="parameter"><code>type</code></em> argument is supplied,
139 <span><strong class="command">dig</strong></span> will perform a lookup for an
146 <div class="refsect1" lang="en">
147 <a name="id2572264"></a><h2>OPTIONS</h2>
149 The <code class="option">-b</code> option sets the source IP address of the query
150 to <em class="parameter"><code>address</code></em>. This must be a valid
152 one of the host's network interfaces or "0.0.0.0" or "::". An optional
154 may be specified by appending "#<port>"
157 The default query class (IN for internet) is overridden by the
158 <code class="option">-c</code> option. <em class="parameter"><code>class</code></em> is
160 class, such as HS for Hesiod records or CH for CHAOSNET records.
163 The <code class="option">-f</code> option makes <span><strong class="command">dig </strong></span>
165 in batch mode by reading a list of lookup requests to process from the
166 file <em class="parameter"><code>filename</code></em>. The file contains a
168 queries, one per line. Each entry in the file should be organised in
169 the same way they would be presented as queries to
170 <span><strong class="command">dig</strong></span> using the command-line interface.
173 If a non-standard port number is to be queried, the
174 <code class="option">-p</code> option is used. <em class="parameter"><code>port#</code></em> is
175 the port number that <span><strong class="command">dig</strong></span> will send its
177 instead of the standard DNS port number 53. This option would be used
178 to test a name server that has been configured to listen for queries
179 on a non-standard port number.
182 The <code class="option">-4</code> option forces <span><strong class="command">dig</strong></span>
184 use IPv4 query transport. The <code class="option">-6</code> option forces
185 <span><strong class="command">dig</strong></span> to only use IPv6 query transport.
188 The <code class="option">-t</code> option sets the query type to
189 <em class="parameter"><code>type</code></em>. It can be any valid query type
191 supported in BIND9. The default query type "A", unless the
192 <code class="option">-x</code> option is supplied to indicate a reverse lookup.
193 A zone transfer can be requested by specifying a type of AXFR. When
194 an incremental zone transfer (IXFR) is required,
195 <em class="parameter"><code>type</code></em> is set to <code class="literal">ixfr=N</code>.
196 The incremental zone transfer will contain the changes made to the zone
197 since the serial number in the zone's SOA record was
198 <em class="parameter"><code>N</code></em>.
201 The <code class="option">-q</code> option sets the query name to
202 <em class="parameter"><code>name</code></em>. This useful do distingish the
203 <em class="parameter"><code>name</code></em> from other arguments.
206 Reverse lookups - mapping addresses to names - are simplified by the
207 <code class="option">-x</code> option. <em class="parameter"><code>addr</code></em> is
209 address in dotted-decimal notation, or a colon-delimited IPv6 address.
210 When this option is used, there is no need to provide the
211 <em class="parameter"><code>name</code></em>, <em class="parameter"><code>class</code></em> and
212 <em class="parameter"><code>type</code></em> arguments. <span><strong class="command">dig</strong></span>
213 automatically performs a lookup for a name like
214 <code class="literal">11.12.13.10.in-addr.arpa</code> and sets the
216 class to PTR and IN respectively. By default, IPv6 addresses are
217 looked up using nibble format under the IP6.ARPA domain.
218 To use the older RFC1886 method using the IP6.INT domain
219 specify the <code class="option">-i</code> option. Bit string labels (RFC2874)
220 are now experimental and are not attempted.
223 To sign the DNS queries sent by <span><strong class="command">dig</strong></span> and
225 responses using transaction signatures (TSIG), specify a TSIG key file
226 using the <code class="option">-k</code> option. You can also specify the TSIG
227 key itself on the command line using the <code class="option">-y</code> option;
228 <em class="parameter"><code>hmac</code></em> is the type of the TSIG, default HMAC-MD5,
229 <em class="parameter"><code>name</code></em> is the name of the TSIG key and
230 <em class="parameter"><code>key</code></em> is the actual key. The key is a
232 encoded string, typically generated by
233 <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
235 Caution should be taken when using the <code class="option">-y</code> option on
236 multi-user systems as the key can be visible in the output from
237 <span class="citerefentry"><span class="refentrytitle">ps</span>(1)</span>
238 or in the shell's history file. When
239 using TSIG authentication with <span><strong class="command">dig</strong></span>, the name
240 server that is queried needs to know the key and algorithm that is
241 being used. In BIND, this is done by providing appropriate
242 <span><strong class="command">key</strong></span> and <span><strong class="command">server</strong></span> statements in
243 <code class="filename">named.conf</code>.
246 <div class="refsect1" lang="en">
247 <a name="id2649124"></a><h2>QUERY OPTIONS</h2>
248 <p><span><strong class="command">dig</strong></span>
249 provides a number of query options which affect
250 the way in which lookups are made and the results displayed. Some of
251 these set or reset flag bits in the query header, some determine which
252 sections of the answer get printed, and others determine the timeout
253 and retry strategies.
256 Each query option is identified by a keyword preceded by a plus sign
257 (<code class="literal">+</code>). Some keywords set or reset an
258 option. These may be preceded
259 by the string <code class="literal">no</code> to negate the meaning of
261 keywords assign values to options like the timeout interval. They
262 have the form <code class="option">+keyword=value</code>.
263 The query options are:
266 <div class="variablelist"><dl>
267 <dt><span class="term"><code class="option">+[no]tcp</code></span></dt>
269 Use [do not use] TCP when querying name servers. The default
270 behaviour is to use UDP unless an AXFR or IXFR query is
272 which case a TCP connection is used.
274 <dt><span class="term"><code class="option">+[no]vc</code></span></dt>
276 Use [do not use] TCP when querying name servers. This alternate
277 syntax to <em class="parameter"><code>+[no]tcp</code></em> is
278 provided for backwards
279 compatibility. The "vc" stands for "virtual circuit".
281 <dt><span class="term"><code class="option">+[no]ignore</code></span></dt>
283 Ignore truncation in UDP responses instead of retrying with TCP.
285 default, TCP retries are performed.
287 <dt><span class="term"><code class="option">+domain=somename</code></span></dt>
289 Set the search list to contain the single domain
290 <em class="parameter"><code>somename</code></em>, as if specified in
292 <span><strong class="command">domain</strong></span> directive in
293 <code class="filename">/etc/resolv.conf</code>, and enable
295 processing as if the <em class="parameter"><code>+search</code></em>
298 <dt><span class="term"><code class="option">+[no]search</code></span></dt>
300 Use [do not use] the search list defined by the searchlist or
302 directive in <code class="filename">resolv.conf</code> (if
304 The search list is not used by default.
306 <dt><span class="term"><code class="option">+[no]showsearch</code></span></dt>
308 Perform [do not perform] a search showing intermediate
311 <dt><span class="term"><code class="option">+[no]defname</code></span></dt>
313 Deprecated, treated as a synonym for <em class="parameter"><code>+[no]search</code></em>
315 <dt><span class="term"><code class="option">+[no]aaonly</code></span></dt>
317 Sets the "aa" flag in the query.
319 <dt><span class="term"><code class="option">+[no]aaflag</code></span></dt>
321 A synonym for <em class="parameter"><code>+[no]aaonly</code></em>.
323 <dt><span class="term"><code class="option">+[no]adflag</code></span></dt>
325 Set [do not set] the AD (authentic data) bit in the query. The
327 currently has a standard meaning only in responses, not in
329 but the ability to set the bit in the query is provided for
332 <dt><span class="term"><code class="option">+[no]cdflag</code></span></dt>
334 Set [do not set] the CD (checking disabled) bit in the query.
336 requests the server to not perform DNSSEC validation of
339 <dt><span class="term"><code class="option">+[no]cl</code></span></dt>
341 Display [do not display] the CLASS when printing the record.
343 <dt><span class="term"><code class="option">+[no]ttlid</code></span></dt>
345 Display [do not display] the TTL when printing the record.
347 <dt><span class="term"><code class="option">+[no]recurse</code></span></dt>
349 Toggle the setting of the RD (recursion desired) bit in the
351 This bit is set by default, which means <span><strong class="command">dig</strong></span>
352 normally sends recursive queries. Recursion is automatically
354 when the <em class="parameter"><code>+nssearch</code></em> or
355 <em class="parameter"><code>+trace</code></em> query options are
358 <dt><span class="term"><code class="option">+[no]nssearch</code></span></dt>
360 When this option is set, <span><strong class="command">dig</strong></span>
362 authoritative name servers for the zone containing the name
364 looked up and display the SOA record that each name server has
368 <dt><span class="term"><code class="option">+[no]trace</code></span></dt>
370 Toggle tracing of the delegation path from the root name servers
372 the name being looked up. Tracing is disabled by default. When
373 tracing is enabled, <span><strong class="command">dig</strong></span> makes
375 resolve the name being looked up. It will follow referrals from
377 root servers, showing the answer from each server that was used
381 <dt><span class="term"><code class="option">+[no]cmd</code></span></dt>
383 toggles the printing of the initial comment in the output
385 the version of <span><strong class="command">dig</strong></span> and the query
387 been applied. This comment is printed by default.
389 <dt><span class="term"><code class="option">+[no]short</code></span></dt>
391 Provide a terse answer. The default is to print the answer in a
394 <dt><span class="term"><code class="option">+[no]identify</code></span></dt>
396 Show [or do not show] the IP address and port number that
398 answer when the <em class="parameter"><code>+short</code></em> option
400 short form answers are requested, the default is not to show the
401 source address and port number of the server that provided the
404 <dt><span class="term"><code class="option">+[no]comments</code></span></dt>
406 Toggle the display of comment lines in the output. The default
410 <dt><span class="term"><code class="option">+[no]stats</code></span></dt>
412 This query option toggles the printing of statistics: when the
414 was made, the size of the reply and so on. The default
416 to print the query statistics.
418 <dt><span class="term"><code class="option">+[no]qr</code></span></dt>
420 Print [do not print] the query as it is sent.
421 By default, the query is not printed.
423 <dt><span class="term"><code class="option">+[no]question</code></span></dt>
425 Print [do not print] the question section of a query when an
427 returned. The default is to print the question section as a
430 <dt><span class="term"><code class="option">+[no]answer</code></span></dt>
432 Display [do not display] the answer section of a reply. The
436 <dt><span class="term"><code class="option">+[no]authority</code></span></dt>
438 Display [do not display] the authority section of a reply. The
439 default is to display it.
441 <dt><span class="term"><code class="option">+[no]additional</code></span></dt>
443 Display [do not display] the additional section of a reply.
444 The default is to display it.
446 <dt><span class="term"><code class="option">+[no]all</code></span></dt>
448 Set or clear all display flags.
450 <dt><span class="term"><code class="option">+time=T</code></span></dt>
453 Sets the timeout for a query to
454 <em class="parameter"><code>T</code></em> seconds. The default time
456 An attempt to set <em class="parameter"><code>T</code></em> to less
458 in a query timeout of 1 second being applied.
460 <dt><span class="term"><code class="option">+tries=T</code></span></dt>
462 Sets the number of times to try UDP queries to server to
463 <em class="parameter"><code>T</code></em> instead of the default, 3.
465 <em class="parameter"><code>T</code></em> is less than or equal to
467 tries is silently rounded up to 1.
469 <dt><span class="term"><code class="option">+retry=T</code></span></dt>
471 Sets the number of times to retry UDP queries to server to
472 <em class="parameter"><code>T</code></em> instead of the default, 2.
474 <em class="parameter"><code>+tries</code></em>, this does not include
478 <dt><span class="term"><code class="option">+ndots=D</code></span></dt>
480 Set the number of dots that have to appear in
481 <em class="parameter"><code>name</code></em> to <em class="parameter"><code>D</code></em> for it to be
482 considered absolute. The default value is that defined using
484 ndots statement in <code class="filename">/etc/resolv.conf</code>, or 1 if no
485 ndots statement is present. Names with fewer dots are
487 relative names and will be searched for in the domains listed in
489 <code class="option">search</code> or <code class="option">domain</code> directive in
490 <code class="filename">/etc/resolv.conf</code>.
492 <dt><span class="term"><code class="option">+bufsize=B</code></span></dt>
494 Set the UDP message buffer size advertised using EDNS0 to
495 <em class="parameter"><code>B</code></em> bytes. The maximum and minimum sizes
496 of this buffer are 65535 and 0 respectively. Values outside
497 this range are rounded up or down appropriately.
498 Values other than zero will cause a EDNS query to be sent.
500 <dt><span class="term"><code class="option">+edns=#</code></span></dt>
502 Specify the EDNS version to query with. Valid values
503 are 0 to 255. Setting the EDNS version will cause a
504 EDNS query to be sent. <code class="option">+noedns</code> clears the
505 remembered EDNS version.
507 <dt><span class="term"><code class="option">+[no]multiline</code></span></dt>
509 Print records like the SOA records in a verbose multi-line
510 format with human-readable comments. The default is to print
511 each record on a single line, to facilitate machine parsing
512 of the <span><strong class="command">dig</strong></span> output.
514 <dt><span class="term"><code class="option">+[no]fail</code></span></dt>
516 Do not try the next server if you receive a SERVFAIL. The
518 to not try the next server which is the reverse of normal stub
522 <dt><span class="term"><code class="option">+[no]besteffort</code></span></dt>
524 Attempt to display the contents of messages which are malformed.
525 The default is to not display malformed answers.
527 <dt><span class="term"><code class="option">+[no]dnssec</code></span></dt>
529 Requests DNSSEC records be sent by setting the DNSSEC OK bit
531 in the OPT record in the additional section of the query.
533 <dt><span class="term"><code class="option">+[no]sigchase</code></span></dt>
535 Chase DNSSEC signature chains. Requires dig be compiled with
538 <dt><span class="term"><code class="option">+trusted-key=####</code></span></dt>
541 Specifies a file containing trusted keys to be used with
542 <code class="option">+sigchase</code>. Each DNSKEY record must be
546 If not specified <span><strong class="command">dig</strong></span> will look for
547 <code class="filename">/etc/trusted-key.key</code> then
548 <code class="filename">trusted-key.key</code> in the current directory.
551 Requires dig be compiled with -DDIG_SIGCHASE.
554 <dt><span class="term"><code class="option">+[no]topdown</code></span></dt>
556 When chasing DNSSEC signature chains perform a top down
558 Requires dig be compiled with -DDIG_SIGCHASE.
565 <div class="refsect1" lang="en">
566 <a name="id2650042"></a><h2>MULTIPLE QUERIES</h2>
568 The BIND 9 implementation of <span><strong class="command">dig </strong></span>
570 specifying multiple queries on the command line (in addition to
571 supporting the <code class="option">-f</code> batch file option). Each of those
572 queries can be supplied with its own set of flags, options and query
576 In this case, each <em class="parameter"><code>query</code></em> argument
578 individual query in the command-line syntax described above. Each
579 consists of any of the standard options and flags, the name to be
580 looked up, an optional query type and class and any query options that
581 should be applied to that query.
584 A global set of query options, which should be applied to all queries,
585 can also be supplied. These global query options must precede the
586 first tuple of name, class, type, options, flags, and query options
587 supplied on the command line. Any global query options (except
588 the <code class="option">+[no]cmd</code> option) can be
589 overridden by a query-specific set of query options. For example:
591 <pre class="programlisting">
592 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
595 shows how <span><strong class="command">dig</strong></span> could be used from the
597 to make three lookups: an ANY query for <code class="literal">www.isc.org</code>, a
598 reverse lookup of 127.0.0.1 and a query for the NS records of
599 <code class="literal">isc.org</code>.
601 A global query option of <em class="parameter"><code>+qr</code></em> is
603 that <span><strong class="command">dig</strong></span> shows the initial query it made
605 lookup. The final query has a local query option of
606 <em class="parameter"><code>+noqr</code></em> which means that <span><strong class="command">dig</strong></span>
607 will not print the initial query when it looks up the NS records for
608 <code class="literal">isc.org</code>.
611 <div class="refsect1" lang="en">
612 <a name="id2650196"></a><h2>IDN SUPPORT</h2>
614 If <span><strong class="command">dig</strong></span> has been built with IDN (internationalized
615 domain name) support, it can accept and display non-ASCII domain names.
616 <span><strong class="command">dig</strong></span> appropriately converts character encoding of
617 domain name before sending a request to DNS server or displaying a
618 reply from the server.
619 If you'd like to turn off the IDN support for some reason, defines
620 the <code class="envar">IDN_DISABLE</code> environment variable.
621 The IDN support is disabled if the variable is set when
622 <span><strong class="command">dig</strong></span> runs.
625 <div class="refsect1" lang="en">
626 <a name="id2650225"></a><h2>FILES</h2>
627 <p><code class="filename">/etc/resolv.conf</code>
629 <p><code class="filename">${HOME}/.digrc</code>
632 <div class="refsect1" lang="en">
633 <a name="id2650246"></a><h2>SEE ALSO</h2>
634 <p><span class="citerefentry"><span class="refentrytitle">host</span>(1)</span>,
635 <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
636 <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>,
637 <em class="citetitle">RFC1035</em>.
640 <div class="refsect1" lang="en">
641 <a name="id2650352"></a><h2>BUGS</h2>
643 There are probably too many query options.
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