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NAME    [Toc]    [Back]

       dig - DNS lookup utility

SYNOPSIS    [Toc]    [Back]

       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... ]

DESCRIPTION    [Toc]    [Back]

       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).

SIMPLE USAGE    [Toc]    [Back]

       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  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
	      supplied, dig will perform a lookup for an A record.

OPTIONS    [Toc]    [Back]

       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-standard
       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	transfer
  can be requested by specifying a type of AXFR. When an incremental
       zone transfer (IXFR) is required, type is set to ixfr=N.  The incremental
  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 colondelimited
 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  transaction
  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    [Toc]    [Back]

       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 strategies.

       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:

	      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 given.

	      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 compatibilty with
	      old versions of dig where it set an unimplemented resolver flag.

	      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 provided
 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 identifying
 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  supplied
  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 section
	      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 format
 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 malformed.
	      The default is to not display malformed answers.

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

MULTIPLE QUERIES    [Toc]    [Back]

       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 standard
 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

       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.

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

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

BUGS    [Toc]    [Back]

       There are probably too many query options.

BIND9				 Jun 30, 2000				DIG(1)
[ Back ]
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