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 ]  [
       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
       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
       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
              supplied, 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.

       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 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 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-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.

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
       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
       +keyword=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
              This option does nothing. It is provided for compatibilty with
              old versions of dig where it set an unimplemented resolver flag.

       +[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
              provided 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]recursive
              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
              identifying 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
              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
              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 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.

       +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
              format 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 the OPT record in the additional section of the
              query.

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
       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
       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

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

BUGS
       There are probably too many query options.



BIND9                            Jun 30, 2000                           DIG(1)