


DIG(1)                        BIND9                        DIG(1)


NAME
       dig - DNS lookup utility

SYNOPSIS
       dig [@server] [-b address] [-c class] [-f filename]
           [-k filename] [-p port#] [-q name] [-t type] [-x addr]
           [-y [hmac:]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 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 BIND 9 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 arguments.

       The IN and CH class names overlap with the IN and CH top
       level domains names. Either use the -t and -c options to
       specify the type and class or use the -q the specify the
       domain name or use "IN." and "CH." when looking up these
       top level domains.

SIMPLE USAGE
       A typical invocation of dig looks like:

            dig @server name type

       where:

       server



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           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 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 organized 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 BIND 9. The default
       query type is "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



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       changes made to the zone since the serial number in the
       zone's SOA record was N.

       The -q option sets the query name to name. This useful do
       distinguish the name from other arguments.

       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 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; hmac
       is the type of the TSIG, default HMAC-MD5, 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 behavior is to use UDP unless an AXFR or IXFR
           query is requested, in which case a TCP connection is
           used.




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       +[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]showsearch
           Perform [do not perform] a search showing intermediate
           results.

       +[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 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]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



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           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 behavior 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



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           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
           timeout 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.
           Values other than zero will cause a EDNS query to be
           sent.

       +edns=#
           Specify the EDNS version to query with. Valid values



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           are 0 to 255. Setting the EDNS version will cause a
           EDNS query to be sent.  +noedns clears the remembered
           EDNS version.

       +[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 behavior.

       +[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=####
           Specifies a file containing trusted keys to be used
           with +sigchase. Each DNSKEY record must be on its own
           line.

           If not specified dig will look for
           /etc/trusted-key.key then trusted-key.key in the
           current directory.

           Requires dig be compiled with -DDIG_SIGCHASE.

       +[no]topdown
           When chasing DNSSEC signature chains perform a
           top-down validation. 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



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       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.

IDN SUPPORT
       If dig has been built with IDN (internationalized domain
       name) support, it can accept and display non-ASCII domain
       names.  dig appropriately converts character encoding of
       domain name before sending a request to DNS server or
       displaying a reply from the server. If you'd like to turn
       off the IDN support for some reason, defines the
       IDN_DISABLE environment variable. The IDN support is
       disabled if the variable is set when dig runs.

FILES
       /etc/resolv.conf

       ${HOME}/.digrc

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

BUGS
       There are probably too many query options.

COPYRIGHT
       Copyright (C) 2004-2007 Internet Systems Consortium, Inc.
       ("ISC")
       Copyright (C) 2000-2003 Internet Software Consortium.









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