dig

DIG(1)                      General Commands Manual                     DIG(1)

NAME
     dig — send domain name query packets to name servers

SYNOPSIS
     dig [@server] domain [⟨query-type⟩] [⟨query-class⟩] [+query-option⟩]
         [-dig-option⟩] [%comment]

DESCRIPTION
     Dig (domain information groper) is a flexible command line tool which can
     be used to gather information from the Domain Name System servers.  Dig
     has two modes: simple interactive mode for a single query, and batch mode
     which executes a query for each in a list of several query lines. All
     query options are accessible from the command line.

     The usual simple use of dig will take the form:

                 dig @server domain query-type query-class

     where:

     server      may be either a domain name or a dot-notation Internet
                 address. If this optional field is omitted, dig will attempt
                 to use the default name server for your machine.

                 Note: If a domain name is specified, this will be resolved
                 using the domain name system resolver (i.e., BIND). If your
                 system does not support DNS, you may have to specify a dot-
                 notation address.  Alternatively, if there is a server at
                 your disposal somewhere,  all that is required is that
                 /etc/resolv.conf be present and indicate where the default
                 name servers reside,  so that server itself can be resolved.
                 See resolver(5) for information on /etc/resolv.conf.
                 WARNING: Changing /etc/resolv.conf will affect both the
                 standard resolver library and (potentially) several programs
                 which use it.  As an option, the user may set the environment
                 variable LOCALRES to name a file which is to be used instead
                 of /etc/resolv.conf (LOCALRES is specific to the dig resolver
                 and is not referenced by the standard resolver).  If the
                 LOCALRES variable is not set or the specified file is not
                 readable, then /etc/resolv.conf will be used.

     domain      is the domain name for which you are requesting information.
                 See the -x option (documented in the OTHER OPTIONS subsection
                 of this section) for convenient way to specify inverse
                 address query.

     query-type  is the type of information (DNS query type) that you are
                 requesting. If omitted, the default is “a” (T_A = address).
                 The following types are recognized:

                 a       T_A        network address
                 any     T_ANY      all/any information about specified domain
                 mx      T_MX       mail exchanger for the domain
                 ns      T_NS       name servers
                 soa     T_SOA      zone of authority record
                 hinfo   T_HINFO    host information
                 axfr    T_AXFR     zone transfer (must ask an authoritative
                                    server)
                 txt     T_TXT      arbitrary number of strings

                 (See RFC 1035 for the complete list.)

     query-class
                 is the network class requested in the query. If omitted, the
                 default is “in” (C_IN = Internet).  The following classes are
                 recognized:

                 in      C_IN       Internet class domain
                 any     C_ANY      all/any class information

                 (See RFC 1035 for the complete list.)

                 Note: Any” can be used to specify a class and/or a type of
                 query.  Dig will parse the first occurrence of “any” to mean
                 query-type = T_ANY.  To specify query-class = C_ANY, you must
                 either specify “any” twice, or set query-class using the -c
                 option (see below).

   OTHER OPTIONS
     %ignored-comment
                 “%” is used to included an argument that is simply not
                 parsed.  This may be useful  if running dig in batch mode.
                 Instead of resolving every @server-domain-name in a list of
                 queries, you can avoid the overhead of doing so, and still
                 have the domain name on the command line as a reference.
                 Example:

                             dig @128.9.0.32 %venera.isi.edu mx isi.edu

     -dig option⟩
                 “-” is used to specify an option which affects the operation
                 of dig.  The following options are currently available
                 (although not guaranteed to be useful):

                 -x dot-notation-address
                             Convenient form to specify inverse address
                             mapping.  Instead of “dig
                             32.0.9.128.in-addr.arpa”, one can simply “dig -x
                             128.9.0.32”.

                 -f file     File for dig batch mode. The file contains a list
                             of query specifications ( dig command lines)
                             which are to be executed successively.  Lines
                             beginning with ‘;’, ‘#’, or ‘\n’ are ignored.
                             Other options may still appear on command line,
                             and will be in effect for each batch query.

                 -T time     Time in seconds between start of successive
                             queries when running in batch mode. Can be used
                             to keep two or more batch dig commands running
                             roughly in sync.  Default is zero.

                 -p port     Port number. Query a name server listening to a
                             non-standard port number.  Default is 53.

                 -P[ping-string]
                             After query returns, execute a ping(8) command
                             for response time comparison.  This rather
                             unelegantly makes a call to the shell.  The last
                             three lines of statistics is printed for the
                             command:

                                         ping -s -server_name -56 -3

                             If the optional “ping_string” is present, it
                             replaces “ping -s” in the shell command.

                 -t query-type
                             Specify type of query.  May specify either an
                             integer value to be included in the type field or
                             use the abbreviated mnemonic as discussed above
                             (i.e., mx = T_MX).

                 -c query-class
                             Specify class of query. May specify either an
                             integer value to be included in the class field
                             or use the abbreviated mnemonic as discussed
                             above (i.e., in = C_IN).

                 -k keydir:keyname
                             Sign the query with the TSIG key named keyname
                             that is in the directory keydir.

                 -envsav     This flag specifies that the dig environment
                             (defaults, print options, etc.), after all of the
                             arguments are parsed, should be saved to a file
                             to become the default environment.  This is
                             useful if you do not like the standard set of
                             defaults and do not desire to include a large
                             number of options each time dig is used.  The
                             environment consists of resolver state variable
                             flags, timeout, and retries as well as the flags
                             detailing dig output (see below).  If the shell
                             environment variable LOCALDEF is set to the name
                             of a file, this is where the default dig
                             environment is saved.  If not, the file “DiG.env”
                             is created in the current working directory.

                             Note: LOCALDEF is specific to the dig resolver,
                             and will not affect operation of the standard
                             resolver library.

                             Each time dig is executed, it looks for
                             “./DiG.env” or the file specified by the shell
                             environment variable LOCALDEF.  If such file
                             exists and is readable, then the environment is
                             restored from this file before any arguments are
                             parsed.

                 -envset     This flag only affects batch query runs. When
                             “-envset” is specified on a line in a dig batch
                             file, the dig environment after the arguments are
                             parsed becomes the default environment for the
                             duration of the batch file, or until the next
                             line which specifies “-envset”.

                 -[no] stick
                             This flag only affects batch query runs.  It
                             specifies that the dig environment (as read
                             initially or set by “-envset” switch) is to be
                             restored before each query (line) in a dig batch
                             file.  The default “-nostick” means that the dig
                             environment does not stick, hence options
                             specified on a single line in a dig batch file
                             will remain in effect for subsequent lines (i.e.
                             they are not restored to the “sticky” default).

     +query-option⟩
                 “+” is used to specify an option to be changed in the query
                 packet or to change dig output specifics. Many of these are
                 the same parameters accepted by nslookup(8).  If an option
                 requires a parameter, the form is as follows:

                             + keyword [=value]

                 Most keywords can be abbreviated.  Parsing of the “+” options
                 is very  simplistic — a value must not be separated from its
                 keyword by white space. The following keywords are currently
                 available:

                 Keyword      Abbrev.  Meaning [default]

                 [no] debug     (deb)    turn on/off debugging mode [deb]
                 [no] d2                 turn on/off extra debugging mode
                                         [nod2]
                 [no] recurse   (rec)    use/don't use recursive lookup [rec]
                 retry=#       (ret)     set number of retries to # [4]
                 time=#        (ti)      set timeout length to # seconds [4]
                 [no] ko                 keep open option (implies vc) [noko]
                 [no] vc                 use/don't use virtual circuit [novc]
                 [no] defname   (def)    use/don't use default domain name
                                         [def]
                 [no] search    (sea)    use/don't use domain search list
                                         [sea]
                 domain=NAME   (do)      set default domain name to NAME
                 [no] ignore    (i)      ignore/don't ignore trunc. errors
                                         [noi]
                 [no] primary   (pr)     use/don't use primary server [nopr]
                 [no] aaonly    (aa)     authoritative query only flag [noaa]
                 [no] cmd                echo parsed arguments [cmd]
                 [no] stats     (st)     print query statistics [st]
                 [no] Header    (H)      print basic header [H]
                 [no] header    (he)     print header flags [he]
                 [no] ttlid     (tt)     print TTLs [tt]
                 [no] cl                 print class info [nocl]
                 [no] qr                 print outgoing query [noqr]
                 [no] reply     (rep)    print reply [rep]
                 [no] ques      (qu)     print question section [qu]
                 [no] answer    (an)     print answer section [an]
                 [no] author    (au)     print authoritative section [au]
                 [no] addit     (ad)     print additional section [ad]
                 pfdef                   set to default print flags
                 pfmin                   set to minimal default print flags
                 pfset=#                 set print flags to # (# can be
                                         hex/octal/decimal)
                 pfand=#                 bitwise and print flags with #
                 pfor=#                  bitwise or print flags with #

                 The retry and time options affect the retransmission strategy
                 used by the resolver library when sending datagram queries.
                 The algorithm is as follows:

                       for i = 0 to retry - 1
                           for j = 1 to num_servers
                               send_query
                               wait((time * (2**i)) / num_servers)
                           end
                       end

                 (Note: dig always uses a value of 1 for “num_servers”.)

   DETAILS
     Dig once required a slightly modified version of the BIND resolver(3)
     library.  As of BIND 4.9, BIND's resolver has been augmented to work
     properly with dig.  Essentially, dig is a straight-forward (albeit not
     pretty) effort of parsing arguments and setting appropriate parameters.
     Dig uses resolver(3) routines res_init(), res_mkquery(), res_send() as
     well as accessing the _res structure.

ENVIRONMENT
     LOCALRES    file to use in place of Pa /etc/resolv.conf
     LOCALDEF    default environment file

     See also the explanation of the -envsav, -envset, and -[no] stick
     options, above.

FILES
     /etc/resolv.conf
                         initial domain name and name server addresses
     ./DiG.env           default save file for default options

SEE ALSO
     named(8), resolver(3), resolver(5), nslookup(8).

STANDARDS
     RFC 1035.

AUTHOR
     Steve Hotz hotz@isi.edu

ACKNOWLEDGMENTS
     Dig uses functions from nslookup(8) authored by Andrew Cherenson.

BUGS
     Dig has a serious case of "creeping featurism" -- the result of
     considering several potential uses during it's development.  It would
     probably benefit from a rigorous diet.  Similarly, the print flags and
     granularity of the items they specify make evident their rather ad hoc
     genesis.

     Dig does not consistently exit nicely (with appropriate status) when a
     problem occurs somewhere in the resolver (NOTE: most of the common exit
     cases are handled).  This is particularly annoying when running in batch
     mode.  If it exits abnormally (and is not caught), the entire batch
     aborts; when such an event is trapped, dig simply continues with the next
     query.

4th Berkeley Distribution       August 30, 1990      4th Berkeley Distribution