dig



DIG(1)                                                                  DIG(1)




NAME

       dig - DNS lookup utility


SYNOPSIS

       dig  [  @server  ]  [ -b address ]  [ -c class ]  [ -f filename ]  [ -k
       filename ]  [ -p port# ]  [ -t type ]  [ -x addr ]  [ -y name:key ]   [
       -4 ]  [ -6 ]  [ name ]  [ type ]  [ class ]  [ queryopt... ]

       dig [ -h ]

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


DESCRIPTION

       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 admin-
       istrators use dig to troubleshoot DNS problems because of its flexibil-
       ity, 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 implementa-
       tion 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 arguments.


SIMPLE USAGE

       A typical invocation of dig looks like:

        dig @server name type

       where:

       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  consults
              /etc/resolv.conf and queries the name servers listed there.  The
              reply from the name server that responds is displayed.

       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  sup-
              plied, dig will perform a lookup for an A record.


OPTIONS

       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  or
       "0.0.0.0"  or  "::".  An  optional  port  may be specified by appending
       "#<port>"

       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-standard
       port number.

       The -4 option forces dig to only  use  IPv4  query  transport.  The  -6
       option forces dig to only use IPv6 query transport.

       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 incremen-
       tal 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 11.12.13.10.in-addr.arpa and sets the query
       type and class to PTR and IN respectively. By default,  IPv6  addresses
       are  looked  up  using nibble format under the IP6.ARPA domain.  To use
       the older RFC1886 method  using  the  IP6.INT  domain  specify  the  -i
       option.  Bit  string  labels (RFC2874) are now experimental and are not
       attempted.

       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-key-
       gen(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.


QUERY OPTIONS

       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-
       gies.

       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 +key-
       word=value.  The query options are:

       +[no]tcp
              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.

       +[no]vc
              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".

       +[no]ignore
              Ignore truncation in UDP responses instead of retrying with TCP.
              By default, TCP retries are performed.

       +domain=somename
              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 given.

       +[no]search
              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.

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

       +[no]aaonly
              Sets the "aa" flag in the query.

       +[no]aaflag
              A synonym for +[no]aaonly.

       +[no]adflag
              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.

       +[no]cdflag
              Set [do not set] the CD (checking disabled) bit  in  the  query.
              This  requests  the  server  to not perform DNSSEC validation of
              responses.

       +[no]cl
              Display [do not display] the CLASS when printing the record.

       +[no]ttlid
              Display [do not display] the TTL when printing the record.

       +[no]recurse
              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.

       +[no]nssearch
              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
              zone.

       +[no]trace
              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.

       +[no]cmd
              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.

       +[no]short
              Provide  a terse answer. The default is to print the answer in a
              verbose form.

       +[no]identify
              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
              answer.

       +[no]comments
              Toggle the display of comment lines in the output.  The  default
              is to print comments.

       +[no]stats
              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.

       +[no]qr
              Print  [do  not print] the query as it is sent.  By default, the
              query is not printed.

       +[no]question
              Print [do not print] the question section of  a  query  when  an
              answer is returned. The default is to print the question section
              as a comment.

       +[no]answer
              Display [do not display] the answer  section  of  a  reply.  The
              default is to display it.

       +[no]authority
              Display  [do  not display] the authority section of a reply. The
              default is to display it.

       +[no]additional
              Display [do not display] the additional section of a reply.  The
              default is to display it.

       +[no]all
              Set or clear all display flags.

       +time=T
              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.

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

       +retry=T
              Sets  the  number  of  times to retry UDP queries to server to T
              instead of the default, 2. Unlike +tries, this does not  include
              the initial query.

       +ndots=D
              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.

       +bufsize=B
              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.

       +[no]multiline
              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.

       +[no]fail
              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.

       +[no]besteffort
              Attempt to display the contents of messages which are malformed.
              The default is to not display malformed answers.

       +[no]dnssec
              Requests  DNSSEC  records  be  sent by setting the DNSSEC OK bit
              (DO) in the OPT record in the additional section of the query.

       +[no]sigchase
              Chase DNSSEC signature chains. Requires  dig  be  compiled  with
              -DDIG_SIGCHASE.

       +trusted-key=####
              Specify  a  trusted key to be used with +sigchase.  Requires dig
              be compiled with -DDIG_SIGCHASE.

       +[no]topdown
              When chasing DNSSEC signature chains perform a top down  valida-
              tion.  Requires dig be compiled with -DDIG_SIGCHASE.


MULTIPLE QUERIES

       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
       query.

       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 127.0.0.1 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  127.0.0.1
       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.


FILES

       /etc/resolv.conf

       ${HOME}/.digrc


SEE ALSO

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


BUGS

       There are probably too many query options.



BIND9                            Jun 30, 2000                           DIG(1)

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