Updated: 2021/Apr/14


DIG(1)                              BIND 9                              DIG(1)



NAME
       dig - DNS lookup utility

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

       dig [-h]

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

DESCRIPTION
       dig 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. 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 tries each of
       the servers listed in /etc/resolv.conf. If no usable server addresses
       are found, dig sends the query to the local host.

       When no command-line arguments or options are given, dig performs 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 -r option disables this feature, for
       scripts that need predictable behavior.

       The IN and CH class names overlap with the IN and CH top-level domain
       names. Either use the -t and -c options to specify the type and class,
       use the -q to 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 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; if an address is found there, it queries the
              name server at that address. If either of the -4 or -6 options
              are in use, then only addresses for the corresponding transport
              are tried. If no usable addresses are found, dig sends the query
              to the local host. 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 performs a lookup for an A record.

OPTIONS

       -4     This option indicates that only IPv4 should be used.

       -6     This option indicates that only IPv6 should be used.

       -b address[#port]
              This option sets the source IP address of the query. The address
              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.

       -c class
              This option sets the query class. The default class is IN; other
              classes are HS for Hesiod records or CH for Chaosnet records.

       -f file
              This option sets batch mode, in which dig reads a list of lookup
              requests to process from the given file. Each line in the file
              should be organized in the same way it would be presented as a
              query to dig using the command-line interface.

       -k keyfile
              This option tells named to sign queries using TSIG using a key
              read from the given file. Key files can be generated using
              tsig-keygen. 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.

       -m     This option enables memory usage debugging.

       -p port
              This option sends the query to a non-standard port on the
              server, instead of the default port 53. This option is used to
              test a name server that has been configured to listen for
              queries on a non-standard port number.

       -q name
              This option specifies the domain name to query. This is useful
              to distinguish the name from other arguments.

       -r     This option indicates that options from ${HOME}/.digrc should
              not be read. This is useful for scripts that need predictable
              behavior.

       -t type
              This option indicates the resource record type to query, which
              can be any valid query type. If it is a resource record type
              supported in BIND 9, it can be given by the type mnemonic (such
              as NS or AAAA). 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, set the type to
              ixfr=N. The incremental zone transfer contains all changes made
              to the zone since the serial number in the zone's SOA record was
              N.

              All resource record types can be expressed as TYPEnn, where nn
              is the number of the type. If the resource record type is not
              supported in BIND 9, the result is displayed as described in RFC
              3597.

       -u     This option indicates that print query times should be provided
              in microseconds instead of milliseconds.

       -v     This option prints the version number and exits.

       -x addr
              This option sets simplified reverse lookups, for mapping
              addresses to names. The addr is an IPv4 address in
              dotted-decimal notation, or a colon-delimited IPv6 address. When
              the -x option is used, there is no need to provide the name,
              class, and type arguments.  dig automatically performs a lookup
              for a name like 94.2.0.192.in-addr.arpa and sets the query type
              and class to PTR and IN respectively. IPv6 addresses are looked
              up using nibble format under the IP6.ARPA domain.

       -y [hmac:]keyname:secret
              This option signs queries using TSIG with the given
              authentication key.  keyname is the name of the key, and secret
              is the base64-encoded shared secret. hmac is the name of the key
              algorithm; valid choices are hmac-md5, hmac-sha1, hmac-sha224,
              hmac-sha256, hmac-sha384, or hmac-sha512. If hmac is not
              specified, the default is hmac-md5; if MD5 was disabled, the
              default is hmac-sha256.

       NOTE:
          Only the -k option should be used, rather than the -y option,
          because with -y the shared secret is supplied as a command-line
          argument in clear text. This may be visible in the output from ps1
          or in a history file maintained by the user's shell.

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. Keywords may be abbreviated, provided the abbreviation
       is unambiguous; for example, +cd is equivalent to +cdflag. The query
       options are:

       +[no]aaflag
              This option is a synonym for +[no]aaonly.

       +[no]aaonly
              This option sets the aa flag in the query.

       +[no]additional
              This option displays [or does not display] the additional
              section of a reply. The default is to display it.

       +[no]adflag
              This option sets [or does not set] the AD (authentic data) bit
              in the query. This requests the server to return whether all of
              the answer and authority sections have been validated as secure,
              according to the security policy of the server. AD=1 indicates
              that all records have been validated as secure and the answer is
              not from a OPT-OUT range. AD=0 indicates that some part of the
              answer was insecure or not validated.  This bit is set by
              default.

       +[no]all
              This option sets or clears all display flags.

       +[no]answer
              This option displays [or does not display] the answer section of
              a reply. The default is to display it.

       +[no]authority
              This option displays [or does not display] the authority section
              of a reply. The default is to display it.

       +[no]badcookie
              This option retries the lookup with a new server cookie if a
              BADCOOKIE response is received.

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

       +bufsize[=B]
              This option sets the UDP message buffer size advertised using
              EDNS0 to B bytes.  The maximum and minimum sizes of this buffer
              are 65535 and 0, respectively.  +bufsize=0 disables EDNS (use
              +bufsize=0 +edns to send an EDNS message with an advertised size
              of 0 bytes). +bufsize restores the default buffer size.

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

       +[no]class
              This option displays [or does not display] the CLASS when
              printing the record.

       +[no]cmd
              This option toggles the printing of the initial comment in the
              output, identifying the version of dig and the query options
              that have been applied. This option always has a global effect;
              it cannot be set globally and then overridden on a per-lookup
              basis. The default is to print this comment.

       +[no]comments
              This option toggles the display of some comment lines in the
              output, with information about the packet header and OPT
              pseudosection, and the names of the response section. The
              default is to print these comments.

              Other types of comments in the output are not affected by this
              option, but can be controlled using other command-line switches.
              These include +[no]cmd, +[no]question, +[no]stats, and
              +[no]rrcomments.

       +[no]cookie=####
              This option sends [or does not send] a COOKIE EDNS option, with
              an optional value. Replaying a COOKIE from a previous response
              allows the server to identify a previous client. The default is
              +cookie.

              +cookie is also set when +trace is set to better emulate the
              default queries from a nameserver.

       +[no]crypto
              This option toggles the display of cryptographic fields in
              DNSSEC records. The contents of these fields are unnecessary for
              debugging most DNSSEC validation failures and removing them
              makes it easier to see the common failures. The default is to
              display the fields. When omitted, they are replaced by the
              string [omitted] or, in the DNSKEY case, the key ID is displayed
              as the replacement, e.g. [ key id = value ].

       +[no]defname
              This option, which is deprecated, is treated as a synonym for
              +[no]search.

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

       +domain=somename
              This option sets the search list to contain the single domain
              somename, as if specified in a domain directive in
              /etc/resolv.conf, and enables search list processing as if the
              +search option were given.

       +dscp=value
              This option sets the DSCP code point to be used when sending the
              query. Valid DSCP code points are in the range [0...63]. By
              default no code point is explicitly set.

       +[no]edns[=#]
              This option specifies the EDNS version to query with. Valid
              values are 0 to 255.  Setting the EDNS version causes an EDNS
              query to be sent.  +noedns clears the remembered EDNS version.
              EDNS is set to 0 by default.

       +[no]ednsflags[=#]
              This option sets the must-be-zero EDNS flags bits (Z bits) to
              the specified value.  Decimal, hex, and octal encodings are
              accepted. Setting a named flag (e.g., DO) is silently ignored.
              By default, no Z bits are set.

       +[no]ednsnegotiation
              This option enables/disables EDNS version negotiation. By
              default, EDNS version negotiation is enabled.

       +[no]ednsopt[=code[:value]]
              This option specifies the EDNS option with code point code and
              an optional payload of value as a hexadecimal string. code can
              be either an EDNS option name (for example, NSID or ECS) or an
              arbitrary numeric value. +noednsopt clears the EDNS options to
              be sent.

       +[no]expire
              This option sends an EDNS Expire option.

       +[no]fail
              This option indicates that named should try [or not try] the
              next server if a SERVFAIL is received. The default is to not try
              the next server, which is the reverse of normal stub resolver
              behavior.

       +[no]header-only
              This option sends a query with a DNS header without a question
              section. The default is to add a question section. The query
              type and query name are ignored when this is set.

       +[no]identify
              This option shows [or does 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]idnin
              This option processes [or does not process] IDN domain names on
              input. This requires IDN SUPPORT to have been enabled at compile
              time.

              The default is to process IDN input when standard output is a
              tty.  The IDN processing on input is disabled when dig output is
              redirected to files, pipes, and other non-tty file descriptors.

       +[no]idnout
              This option converts [or does not convert] puny code on output.
              This requires IDN SUPPORT to have been enabled at compile time.

              The default is to process puny code on output when standard
              output is a tty. The puny code processing on output is disabled
              when dig output is redirected to files, pipes, and other non-tty
              file descriptors.

       +[no]ignore
              This option ignores [or does not ignore] truncation in UDP
              responses instead of retrying with TCP. By default, TCP retries
              are performed.

       +[no]keepalive
              This option sends [or does not send] an EDNS Keepalive option.

       +[no]keepopen
              This option keeps [or does not keep] the TCP socket open between
              queries, and reuses it rather than creating a new TCP socket for
              each lookup. The default is +nokeepopen.

       +[no]mapped
              This option allows [or does not allow] mapped IPv4-over-IPv6
              addresses to be used. The default is +mapped.

       +[no]multiline
              This option prints [or does not 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.

       +ndots=D
              This option sets the number of dots (D) that must appear in name
              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 are searched for in the
              domains listed in the search or domain directive in
              /etc/resolv.conf if +search is set.

       +[no]nsid
              When enabled, this option includes an EDNS name server ID
              request when sending a query.

       +[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.  Addresses of servers that did not respond are also
              printed.

       +[no]onesoa
              When enabled, this option prints only one (starting) SOA record
              when performing an AXFR. The default is to print both the
              starting and ending SOA records.

       +[no]opcode=value
              When enabled, this option sets (restores) the DNS message opcode
              to the specified value. The default value is QUERY (0).

       +padding=value
              This option pads the size of the query packet using the EDNS
              Padding option to blocks of value bytes. For example,
              +padding=32 causes a 48-byte query to be padded to 64 bytes. The
              default block size is 0, which disables padding; the maximum is
              512. Values are ordinarily expected to be powers of two, such as
              128; however, this is not mandatory. Responses to padded queries
              may also be padded, but only if the query uses TCP or DNS
              COOKIE.

       +[no]qr
              This option toggles the display of the query message as it is
              sent. By default, the query is not printed.

       +[no]question
              This option toggles the display of the question section of a
              query when an answer is returned. The default is to print the
              question section as a comment.

       +[no]raflag
              This option sets [or does not set] the RA (Recursion Available)
              bit in the query. The default is +noraflag. This bit is ignored
              by the server for QUERY.

       +[no]rdflag
              This option is a synonym for +[no]recurse.

       +[no]recurse
              This option toggles 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 option is used.

       +retry=T
              This option 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.

       +[no]rrcomments
              This option toggles the display of per-record comments in the
              output (for example, human-readable key information about DNSKEY
              records). The default is not to print record comments unless
              multiline mode is active.

       +[no]search
              This option uses [or does 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.

              ndots from resolv.conf (default 1), which may be overridden by
              +ndots, determines whether the name is treated as relative and
              hence whether a search is eventually performed.

       +[no]short
              This option toggles whether a terse answer is provided. The
              default is to print the answer in a verbose form. This option
              always has a global effect; it cannot be set globally and then
              overridden on a per-lookup basis.

       +[no]showsearch
              This option performs [or does not perform] a search showing
              intermediate results.

       +[no]sigchase
              This feature is now obsolete and has been removed; use delv
              instead.

       +split=W
              This option splits long hex- or base64-formatted fields in
              resource records into chunks of W characters (where W is rounded
              up to the nearest multiple of 4). +nosplit or +split=0 causes
              fields not to be split at all. The default is 56 characters, or
              44 characters when multiline mode is active.

       +[no]stats
              This option toggles the printing of statistics: when the query
              was made, the size of the reply, etc. The default behavior is to
              print the query statistics as a comment after each lookup.

       +[no]subnet=addr[/prefix-length]
              This option sends [or does not send] an EDNS CLIENT-SUBNET
              option with the specified IP address or network prefix.

              dig +subnet=0.0.0.0/0, or simply dig +subnet=0 for short, sends
              an EDNS CLIENT-SUBNET option with an empty address and a source
              prefix-length of zero, which signals a resolver that the
              client's address information must not be used when resolving
              this query.

       +[no]tcflag
              This option sets [or does not set] the TC (TrunCation) bit in
              the query. The default is +notcflag. This bit is ignored by the
              server for QUERY.

       +[no]tcp
              This option uses [or does not use] TCP when querying name
              servers. The default behavior is to use UDP unless a type any or
              ixfr=N query is requested, in which case the default is TCP.
              AXFR queries always use TCP.

       +timeout=T
              This option sets the timeout for a query to T seconds. The
              default timeout is 5 seconds. An attempt to set T to less than 1
              is silently set to 1.

       +[no]topdown
              This feature is related to dig +sigchase, which is obsolete and
              has been removed. Use delv instead.

       +[no]trace
              This option toggles 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 follows referrals from
              the root servers, showing the answer from each server that was
              used to resolve the lookup.

              If @server is also specified, it affects only the initial query
              for the root zone name servers.

              +dnssec is also set when +trace is set, to better emulate the
              default queries from a name server.

       +tries=T
              This option 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.

       +trusted-key=####
              This option formerly specified trusted keys for use with dig
              +sigchase. This feature is now obsolete and has been removed;
              use delv instead.

       +[no]ttlid
              This option displays [or does not display] the TTL when printing
              the record.

       +[no]ttlunits
              This option displays [or does not display] the TTL in friendly
              human-readable time units of s, m, h, d, and w, representing
              seconds, minutes, hours, days, and weeks. This implies +ttlid.

       +[no]unexpected
              This option accepts [or does not accept] answers from unexpected
              sources.  By default, dig will not accept a reply from a source
              other than the one to which it sent the query.

       +[no]unknownformat
              This option prints all RDATA in unknown RR type presentation
              format (RFC 3597).  The default is to print RDATA for known
              types in the type's presentation format.

       +[no]vc
              This option uses [or does 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]yaml
              When enabled, this option prints the responses (and, if +qr is
              in use, also the outgoing queries) in a detailed YAML format.

       +[no]zflag
              This option sets [or does not set] the last unassigned DNS
              header flag in a DNS query.  This flag is off by default.

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 represents 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 +[no]cmd and
       +[no]short options) 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 can 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
       does 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 a domain name before sending a request
       to a DNS server or displaying a reply from the server.  To turn off IDN
       support, use the parameters +noidnin and +noidnout, or define the
       IDN_DISABLE environment variable.

FILES
       /etc/resolv.conf

       ${HOME}/.digrc

SEE ALSO
       delv(1), host(1), named(8), dnssec-keygen(8), RFC 1035.

BUGS
       There are probably too many query options.

AUTHOR
       Internet Systems Consortium

COPYRIGHT
       2021, Internet Systems Consortium



9.16.12                                                                 DIG(1)