DIG linux command manual

DIG(1)                                                                     DIG(1)

       dig - DNS lookup utility

       dig  [  @server ]  [ -b address ]  [ -c class ]  [ -f filename ]  [ -k
       filename ]  [ -p port# ]  [ -t type ]  [ -x addr ]  [ -y name:key ]  [
       name ]  [ type ]  [ class ]  [ queryopt... ]

       dig [ -h ]

       dig [ global-queryopt... ]  [ query... ]

       dig  (domain  information groper) is a flexible tool for interrogating
       DNS name servers. It performs DNS lookups  and  displays  the  answers
       that  are returned from the name server(s) that were queried. Most DNS
       administrators use dig to troubleshoot DNS  problems  because  of  its
       flexibility,  ease  of  use  and clarity of output. Other lookup tools
       tend to have less functionality than dig.

       Although dig is normally used with command-line arguments, it also has
       a  batch  mode of operation for reading lookup requests from a file. A
       brief summary of its command-line arguments  and  options  is  printed
       when  the  -h  option  is  given.   Unlike earlier versions, the BIND9
       implementation of dig allows multiple lookups to be  issued  from  the
       command line.

       Unless  it  is told to query a specific name server, dig will try each
       of the servers listed in /etc/resolv.conf.

       When no command line arguments or options are given, will  perform  an
       NS query for "." (the root).

       It  is  possible  to set per user defaults for dig via ${HOME}/.digrc.
       This file is read and any options in it are applied before the command
       line arguements.

       A typical invocation of dig looks like:

        dig @server name type


       server is the name or IP address of the name server to query. This can
              be an IPv4  address  in  dotted-decimal  notation  or  an  IPv6
              address  in  colon-delimited notation. When the supplied server
              argument is a hostname, dig resolves that name before  querying
              that  name  server. If no server argument is provided, dig con-
              sults /etc/resolv.conf and  queries  the  name  servers  listed
              there.  The  reply  from  the name server that responds is dis-

       name   is the name of the resource record that is to be looked up.

       type   indicates what type of query is required --  ANY,  A,  MX,  SIG,
              etc.   type can be any valid query type. If no type argument is
              supplied, dig will perform a lookup for an A record.

       The -b option sets the source IP address of the query to address. This
       must be a valid address on one of the host's network interfaces.

       The  default  query  class  (IN  for internet) is overridden by the -c
       option. class is any valid class, such as HS for Hesiod records or  CH
       for CHAOSNET records.

       The  -f  option  makes dig  operate in batch mode by reading a list of
       lookup requests to process from the file filename. The file contains a
       number  of  queries,  one  per  line. Each entry in the file should be
       organised in the same way they would be presented as  queries  to  dig
       using the command-line interface.

       If a non-standard port number is to be queried, the -p option is used.
       port# is the port number that dig will send its queries instead of the
       standard  DNS port number 53. This option would be used to test a name
       server that has been configured to listen for queries on  a  non-stan-
       dard port number.

       The  -t  option sets the query type to type. It can be any valid query
       type which is supported in BIND9. The default query type  "A",  unless
       the -x option is supplied to indicate a reverse lookup.  A zone trans-
       fer can be requested by specifying a type of AXFR. When an incremental
       zone  transfer  (IXFR) is required, type is set to ixfr=N.  The incre-
       mental zone transfer will contain the changes made to the  zone  since
       the serial number in the zone's SOA record was N.

       Reverse  lookups  - mapping addresses to names - are simplified by the
       -x option. addr is an IPv4 address in dotted-decimal  notation,  or  a
       colon-delimited  IPv6  address.  When this option is used, there is no
       need to provide the name, class and type arguments. dig  automatically
       performs  a  lookup  for a name like and sets
       the query type and class to PTR and IN respectively. By default,  IPv6
       addresses are looked up using the IP6.ARPA domain and binary labels as
       defined in RFC2874. To use the older RFC1886 method using the  IP6.INT
       domain and "nibble" labels, specify the -n (nibble) option.

       To sign the DNS queries sent by dig and their responses using transac-
       tion signatures (TSIG), specify a TSIG key file using the  -k  option.
       You can also specify the TSIG key itself on the command line using the
       -y option; name is the name of the TSIG key and key is the actual key.
       The  key  is  a base-64 encoded string, typically generated by dnssec-
       keygen(8).  Caution should be taken when using the -y option on multi-
       user  systems as the key can be visible in the output from ps(1) or in
       the shell's history file. When using TSIG authentication with dig, the
       name  server  that is queried needs to know the key and algorithm that
       is being used. In BIND, this is done by providing appropriate key  and
       server statements in named.conf.

       dig  provides  a number of query options which affect the way in which
       lookups are made and the results displayed. Some of these set or reset
       flag  bits  in  the query header, some determine which sections of the
       answer get printed, and others determine the timeout and retry strate-

       Each  query  option is identified by a keyword preceded by a plus sign
       (+). Some keywords set or reset an option. These may  be  preceded  by
       the  string  no  to negate the meaning of that keyword. Other keywords
       assign values to options like the timeout interval. They have the form
       +keyword=value.  The query options are:

              Use  [do  not  use] TCP when querying name servers. The default
              behaviour is to use  UDP  unless  an  AXFR  or  IXFR  query  is
              requested, in which case a TCP connection is used.

              Use [do not use] TCP when querying name servers. This alternate
              syntax to +[no]tcp is provided for backwards compatibility. The
              "vc" stands for "virtual circuit".

              Ignore  truncation  in  UDP  responses instead of retrying with
              TCP. By default, TCP retries are performed.

              Set the search list to contain the single domain  somename,  as
              if  specified  in  a  domain directive in /etc/resolv.conf, and
              enable search list processing as if  the  +search  option  were

              Use  [do  not use] the search list defined by the searchlist or
              domain directive in resolv.conf (if any).  The search  list  is
              not used by default.

              Deprecated, treated as a synonym for +[no]search

              This option does nothing. It is provided for compatibility with
              old versions of dig where  it  set  an  unimplemented  resolver

              Set  [do not set] the AD (authentic data) bit in the query. The
              AD bit currently has a standard meaning only in responses,  not
              in queries, but the ability to set the bit in the query is pro-
              vided for completeness.

              Set [do not set] the CD (checking disabled) bit in  the  query.
              This  requests  the  server to not perform DNSSEC validation of

              Toggle the setting of the RD (recursion  desired)  bit  in  the
              query.   This  bit  is set by default, which means dig normally
              sends recursive queries. Recursion  is  automatically  disabled
              when the +nssearch or +trace query options are used.

              When this option is set, dig attempts to find the authoritative
              name servers for the zone containing the name being  looked  up
              and  display  the  SOA record that each name server has for the

              Toggle tracing of  the  delegation  path  from  the  root  name
              servers  for  the  name being looked up. Tracing is disabled by
              default. When tracing is enabled, dig makes  iterative  queries
              to  resolve  the name being looked up. It will follow referrals
              from the root servers, showing the answer from each server that
              was used to resolve the lookup.

              toggles the printing of the initial comment in the output iden-
              tifying the version of dig and the query options that have been
              applied. This comment is printed by default.

              Provide a terse answer. The default is to print the answer in a
              verbose form.

              Show [or do not show] the IP address and port number that  sup-
              plied  the  answer  when the +short option is enabled. If short
              form answers are requested, the default  is  not  to  show  the
              source  address and port number of the server that provided the

              Toggle the display of comment lines in the output. The  default
              is to print comments.

              This  query option toggles the printing of statistics: when the
              query was made, the size of the reply and so  on.  The  default
              behaviour is to print the query statistics.

              Print  [do not print] the query as it is sent.  By default, the
              query is not printed.

              Print [do not print] the question section of a  query  when  an
              answer  is  returned. The default is to print the question sec-
              tion as a comment.

              Display [do not display] the answer section  of  a  reply.  The
              default is to display it.

              Display  [do not display] the authority section of a reply. The
              default is to display it.

              Display [do not display] the additional  section  of  a  reply.
              The default is to display it.

              Set or clear all display flags.

              Sets the timeout for a query to T seconds. The default time out
              is 5 seconds.  An attempt to set T to less than 1  will  result
              in a query timeout of 1 second being applied.

              Sets  the  number  of times to retry UDP queries to server to T
              instead of the default, 3. If T is less than or equal to  zero,
              the number of retries is silently rounded up to 1.

              Set  the number of dots that have to appear in name to D for it
              to be considered absolute. The default value  is  that  defined
              using the ndots statement in /etc/resolv.conf, or 1 if no ndots
              statement is present. Names with fewer dots are interpreted  as
              relative  names  and will be searched for in the domains listed
              in the search or domain directive in /etc/resolv.conf.

              Set the UDP message buffer size advertised  using  EDNS0  to  B
              bytes.  The  maximum and minimum sizes of this buffer are 65535
              and 0 respectively. Values outside this range are rounded up or
              down appropriately.

              Print records like the SOA records in a verbose multi-line for-
              mat with human-readable comments. The default is to print  each
              record  on  a single line, to facilitate machine parsing of the
              dig output.

              Do not try the next server  if  you  receive  a  SERVFAIL.  The
              default  is  to not try the next server which is the reverse of
              normal stub resolver behaviour.

              Attempt to display the contents  of  messages  which  are  mal-
              formed.  The default is to not display malformed answers.

              Requests  DNSSEC  records  be sent by setting the DNSSEC OK bit
              (DO) in the OPT record in the additional section of the  query.

       The BIND 9 implementation of dig  supports specifying multiple queries
       on the command line (in addition  to  supporting  the  -f  batch  file
       option).  Each  of  those  queries can be supplied with its own set of
       flags, options and query options.

       In this case, each query argument represent an individual query in the
       command-line syntax described above. Each consists of any of the stan-
       dard options and flags, the name to be looked up,  an  optional  query
       type  and  class  and any query options that should be applied to that

       A global set of query options, which should be applied to all queries,
       can  also  be  supplied.  These  global query options must precede the
       first tuple of name, class, type, options, flags,  and  query  options
       supplied  on  the  command  line. Any global query options (except the
       +[no]cmd option) can be overridden by a query-specific  set  of  query
       options. For example:

       dig +qr www.isc.org any -x isc.org ns +noqr

       shows  how  dig  could  be  used  from  the command line to make three
       lookups: an ANY query for www.isc.org, a reverse lookup  of
       and  a  query for the NS records of isc.org.  A global query option of
       +qr is applied, so that dig shows the initial query it made  for  each
       lookup.  The final query has a local query option of +noqr which means
       that dig will not print the initial query when  it  looks  up  the  NS
       records for isc.org.



       host(1), named(8), dnssec-keygen(8), RFC1035.

       There are probably too many query options.

BIND9                            Jun 30, 2000                          DIG(1)