1DIG(1) BIND9 DIG(1)
2
6 dig - DNS lookup utility
7
9 dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m]
10 [-p port#] [-q name] [-t type] [-x addr] [-y [hmac:]name:key] [-4]
11 [-6] [name] [type] [class] [queryopt...]
12 dig [-h]
14 dig [global-queryopt...] [query...]
16
18 dig (domain information groper) is a flexible tool for interrogating
19 DNS name servers. It performs DNS lookups and displays the answers that
20 are returned from the name server(s) that were queried. Most DNS
21 administrators use dig to troubleshoot DNS problems because of its
22 flexibility, ease of use and clarity of output. Other lookup tools tend
23 to have less functionality than dig.
24 Although dig is normally used with command-line arguments, it also has
26 a batch mode of operation for reading lookup requests from a file. A
27 brief summary of its command-line arguments and options is printed when
28 the -h option is given. Unlike earlier versions, the BIND 9
29 implementation of dig allows multiple lookups to be issued from the
30 command line.
31 Unless it is told to query a specific name server, dig will try each of
33 the servers listed in /etc/resolv.conf.
34 When no command line arguments or options are given, dig will perform
36 an NS query for "." (the root).
37 It is possible to set per-user defaults for dig via ${HOME}/.digrc.
39 This file is read and any options in it are applied before the command
40 line arguments.
41 The IN and CH class names overlap with the IN and CH top level domains
43 names. Either use the -t and -c options to specify the type and class,
44 use the -q the specify the domain name, or use "IN." and "CH." when
45 looking up these top level domains.
46
48 A typical invocation of dig looks like:
49 dig @server name type
51 where:
53 server
55 is the name or IP address of the name server to query. This can be
56 an IPv4 address in dotted-decimal notation or an IPv6 address in
57 colon-delimited notation. When the supplied server argument is a
58 hostname, dig resolves that name before querying that name server.
59 If no server argument is provided, dig consults /etc/resolv.conf
60 and queries the name servers listed there. The reply from the name
61 server that responds is displayed.
62 name
64 is the name of the resource record that is to be looked up.
65 type
67 indicates what type of query is required — ANY, A, MX, SIG, etc.
68 type can be any valid query type. If no type argument is supplied,
69 dig will perform a lookup for an A record.
70
72 The -b option sets the source IP address of the query to address. This
73 must be a valid address on one of the host´s network interfaces or
74 "0.0.0.0" or "::". An optional port may be specified by appending
75 "#<port>"
76 The default query class (IN for internet) is overridden by the -c
78 option. class is any valid class, such as HS for Hesiod records or CH
79 for Chaosnet records.
80 The -f option makes dig operate in batch mode by reading a list of
82 lookup requests to process from the file filename. The file contains a
83 number of queries, one per line. Each entry in the file should be
84 organized in the same way they would be presented as queries to dig
85 using the command-line interface.
86 The -m option enables memory usage debugging.
88 If a non-standard port number is to be queried, the -p option is used.
90 port# is the port number that dig will send its queries instead of the
91 standard DNS port number 53. This option would be used to test a name
92 server that has been configured to listen for queries on a non-standard
93 port number.
94 The -4 option forces dig to only use IPv4 query transport. The -6
96 option forces dig to only use IPv6 query transport.
97 The -t option sets the query type to type. It can be any valid query
99 type which is supported in BIND 9. The default query type is "A",
100 unless the -x option is supplied to indicate a reverse lookup. A zone
101 transfer can be requested by specifying a type of AXFR. When an
102 incremental zone transfer (IXFR) is required, type is set to ixfr=N.
103 The incremental zone transfer will contain the changes made to the zone
104 since the serial number in the zone´s SOA record was N.
105 The -q option sets the query name to name. This useful do distinguish
107 the name from other arguments.
108 Reverse lookups — mapping addresses to names — are simplified by the -x
110 option. addr is an IPv4 address in dotted-decimal notation, or a
111 colon-delimited IPv6 address. When this option is used, there is no
112 need to provide the name, class and type arguments. dig automatically
113 performs a lookup for a name like 11.12.13.10.in-addr.arpa and sets the
114 query type and class to PTR and IN respectively. By default, IPv6
115 addresses are looked up using nibble format under the IP6.ARPA domain.
116 To use the older RFC1886 method using the IP6.INT domain specify the -i
117 option. Bit string labels (RFC2874) are now experimental and are not
118 attempted.
119 To sign the DNS queries sent by dig and their responses using
121 transaction signatures (TSIG), specify a TSIG key file using the -k
122 option. You can also specify the TSIG key itself on the command line
123 using the -y option; hmac is the type of the TSIG, default HMAC-MD5,
124 name is the name of the TSIG key and key is the actual key. The key is
125 a base-64 encoded string, typically generated by dnssec-keygen(8).
126 Caution should be taken when using the -y option on multi-user systems
127 as the key can be visible in the output from ps(1) or in the shell´s
128 history file. When using TSIG authentication with dig, the name server
129 that is queried needs to know the key and algorithm that is being used.
130 In BIND, this is done by providing appropriate key and server
131 statements in named.conf.
132
134 dig provides a number of query options which affect the way in which
135 lookups are made and the results displayed. Some of these set or reset
136 flag bits in the query header, some determine which sections of the
137 answer get printed, and others determine the timeout and retry
138 strategies.
139 Each query option is identified by a keyword preceded by a plus sign
141 (+). Some keywords set or reset an option. These may be preceded by the
142 string no to negate the meaning of that keyword. Other keywords assign
143 values to options like the timeout interval. They have the form
144 +keyword=value. The query options are:
145 +[no]tcp
147 Use [do not use] TCP when querying name servers. The default
148 behavior is to use UDP unless an AXFR or IXFR query is requested,
149 in which case a TCP connection is used.
150 +[no]vc
152 Use [do not use] TCP when querying name servers. This alternate
153 syntax to +[no]tcp is provided for backwards compatibility. The
154 "vc" stands for "virtual circuit".
155 +[no]ignore
157 Ignore truncation in UDP responses instead of retrying with TCP. By
158 default, TCP retries are performed.
159 +domain=somename
161 Set the search list to contain the single domain somename, as if
162 specified in a domain directive in /etc/resolv.conf, and enable
163 search list processing as if the +search option were given.
164 +[no]search
166 Use [do not use] the search list defined by the searchlist or
167 domain directive in resolv.conf (if any). The search list is not
168 used by default.
169 +[no]showsearch
171 Perform [do not perform] a search showing intermediate results.
172 +[no]defname
174 Deprecated, treated as a synonym for +[no]search
175 +[no]aaonly
177 Sets the "aa" flag in the query.
178 +[no]aaflag
180 A synonym for +[no]aaonly.
181 +[no]adflag
183 Set [do not set] the AD (authentic data) bit in the query. This
184 requests the server to return whether all of the answer and
185 authority sections have all been validated as secure according to
186 the security policy of the server. AD=1 indicates that all records
187 have been validated as secure and the answer is not from a OPT-OUT
188 range. AD=0 indicate that some part of the answer was insecure or
189 not validated.
190 +[no]cdflag
192 Set [do not set] the CD (checking disabled) bit in the query. This
193 requests the server to not perform DNSSEC validation of responses.
194 +[no]cl
196 Display [do not display] the CLASS when printing the record.
197 +[no]ttlid
199 Display [do not display] the TTL when printing the record.
200 +[no]recurse
202 Toggle the setting of the RD (recursion desired) bit in the query.
203 This bit is set by default, which means dig normally sends
204 recursive queries. Recursion is automatically disabled when the
205 +nssearch or +trace query options are used.
206 +[no]nssearch
208 When this option is set, dig attempts to find the authoritative
209 name servers for the zone containing the name being looked up and
210 display the SOA record that each name server has for the zone.
211 +[no]trace
213 Toggle tracing of the delegation path from the root name servers
214 for the name being looked up. Tracing is disabled by default. When
215 tracing is enabled, dig makes iterative queries to resolve the name
216 being looked up. It will follow referrals from the root servers,
217 showing the answer from each server that was used to resolve the
218 lookup.
219 +[no]cmd
221 Toggles the printing of the initial comment in the output
222 identifying the version of dig and the query options that have been
223 applied. This comment is printed by default.
224 +[no]short
226 Provide a terse answer. The default is to print the answer in a
227 verbose form.
228 +[no]identify
230 Show [or do not show] the IP address and port number that supplied
231 the answer when the +short option is enabled. If short form answers
232 are requested, the default is not to show the source address and
233 port number of the server that provided the answer.
234 +[no]comments
236 Toggle the display of comment lines in the output. The default is
237 to print comments.
238 +[no]stats
240 This query option toggles the printing of statistics: when the
241 query was made, the size of the reply and so on. The default
242 behavior is to print the query statistics.
243 +[no]qr
245 Print [do not print] the query as it is sent. By default, the query
246 is not printed.
247 +[no]question
249 Print [do not print] the question section of a query when an answer
250 is returned. The default is to print the question section as a
251 comment.
252 +[no]answer
254 Display [do not display] the answer section of a reply. The default
255 is to display it.
256 +[no]authority
258 Display [do not display] the authority section of a reply. The
259 default is to display it.
260 +[no]additional
262 Display [do not display] the additional section of a reply. The
263 default is to display it.
264 +[no]all
266 Set or clear all display flags.
267 +time=T
269 Sets the timeout for a query to T seconds. The default timeout is 5
270 seconds. An attempt to set T to less than 1 will result in a query
271 timeout of 1 second being applied.
272 +tries=T
274 Sets the number of times to try UDP queries to server to T instead
275 of the default, 3. If T is less than or equal to zero, the number
276 of tries is silently rounded up to 1.
277 +retry=T
279 Sets the number of times to retry UDP queries to server to T
280 instead of the default, 2. Unlike +tries, this does not include the
281 initial query.
282 +ndots=D
284 Set the number of dots that have to appear in name to D for it to
285 be considered absolute. The default value is that defined using the
286 ndots statement in /etc/resolv.conf, or 1 if no ndots statement is
287 present. Names with fewer dots are interpreted as relative names
288 and will be searched for in the domains listed in the search or
289 domain directive in /etc/resolv.conf.
290 +bufsize=B
292 Set the UDP message buffer size advertised using EDNS0 to B bytes.
293 The maximum and minimum sizes of this buffer are 65535 and 0
294 respectively. Values outside this range are rounded up or down
295 appropriately. Values other than zero will cause a EDNS query to be
296 sent.
297 +edns=#
299 Specify the EDNS version to query with. Valid values are 0 to 255.
300 Setting the EDNS version will cause a EDNS query to be sent.
301 +noedns clears the remembered EDNS version.
302 +[no]multiline
304 Print records like the SOA records in a verbose multi-line format
305 with human-readable comments. The default is to print each record
306 on a single line, to facilitate machine parsing of the dig output.
307 +[no]onesoa
309 Print only one (starting) SOA record when performing an AXFR. The
310 default is to print both the starting and ending SOA records.
311 +[no]fail
313 Do not try the next server if you receive a SERVFAIL. The default
314 is to not try the next server which is the reverse of normal stub
315 resolver behavior.
316 +[no]besteffort
318 Attempt to display the contents of messages which are malformed.
319 The default is to not display malformed answers.
320 +[no]dnssec
322 Requests DNSSEC records be sent by setting the DNSSEC OK bit (DO)
323 in the OPT record in the additional section of the query.
324 +[no]sigchase
326 Chase DNSSEC signature chains. Requires dig be compiled with
327 -DDIG_SIGCHASE.
328 +trusted-key=####
330 Specifies a file containing trusted keys to be used with +sigchase.
331 Each DNSKEY record must be on its own line.
332 If not specified, dig will look for /etc/trusted-key.key then
334 trusted-key.key in the current directory.
335 Requires dig be compiled with -DDIG_SIGCHASE.
337 +[no]topdown
339 When chasing DNSSEC signature chains perform a top-down validation.
340 Requires dig be compiled with -DDIG_SIGCHASE.
341 +[no]nsid
343 Include an EDNS name server ID request when sending a query.
344
346 The BIND 9 implementation of dig supports specifying multiple queries
347 on the command line (in addition to supporting the -f batch file
348 option). Each of those queries can be supplied with its own set of
349 flags, options and query options.
350 In this case, each query argument represent an individual query in the
352 command-line syntax described above. Each consists of any of the
353 standard options and flags, the name to be looked up, an optional query
354 type and class and any query options that should be applied to that
355 query.
356 A global set of query options, which should be applied to all queries,
358 can also be supplied. These global query options must precede the first
359 tuple of name, class, type, options, flags, and query options supplied
360 on the command line. Any global query options (except the +[no]cmd
361 option) can be overridden by a query-specific set of query options. For
362 example:
363 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
365 shows how dig could be used from the command line to make three
367 lookups: an ANY query for www.isc.org, a reverse lookup of 127.0.0.1
368 and a query for the NS records of isc.org. A global query option of +qr
369 is applied, so that dig shows the initial query it made for each
370 lookup. The final query has a local query option of +noqr which means
371 that dig will not print the initial query when it looks up the NS
372 records for isc.org.
373
375 If dig has been built with IDN (internationalized domain name) support,
376 it can accept and display non-ASCII domain names. dig appropriately
377 converts character encoding of domain name before sending a request to
378 DNS server or displaying a reply from the server. If you´d like to turn
379 off the IDN support for some reason, define the CHARSET=ASCII
380 environment variable. The IDN support is disabled if the variable is
381 set when dig runs.
382
384 Dig return codes are:
385 0: Everything went well, including things like NXDOMAIN
387 1: Usage error
389 8: Couldn´t open batch file
391 9: No reply from server
393 10: Internal error
395
397 /etc/resolv.conf
398 ${HOME}/.digrc
400
402 host(1), named(8), dnssec-keygen(8), RFC1035.
403
405 There are probably too many query options.
406
408 Copyright © 2004-2010 Internet Systems Consortium, Inc. ("ISC")
409 Copyright © 2000-2003 Internet Software Consortium.
410BIND9 Jun 30, 2000 DIG(1)