bin/dig/dig.rst

.. Copyright (C) Internet Systems Consortium, Inc. ("ISC")
..
.. SPDX-License-Identifier: MPL-2.0
..
.. This Source Code Form is subject to the terms of the Mozilla Public
.. License, v. 2.0.  If a copy of the MPL was not distributed with this
.. file, you can obtain one at https://mozilla.org/MPL/2.0/.
..
.. See the COPYRIGHT file distributed with this work for additional
.. information regarding copyright ownership.

.. highlight: console

.. iscman:: dig
.. program:: dig
.. _man_dig:

dig - DNS lookup utility
------------------------

Synopsis
~~~~~~~~
:program:`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...]

:program:`dig` [**-h**]

:program:`dig` [global-queryopt...] [query...]

Description
~~~~~~~~~~~

:program:`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 :program:`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 :program:`dig`.

Although :program:`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 :option:`-h` option is given. The BIND 9
implementation of :program:`dig` allows multiple lookups to be issued from the
command line.

Unless it is told to query a specific name server, :program:`dig` tries each
of the servers listed in ``/etc/resolv.conf``. If no usable server
addresses are found, :program:`dig` sends the query to the local host.

When no command-line arguments or options are given, :program:`dig`
performs an NS query for "." (the root).

It is possible to set per-user defaults for :program:`dig` via
``${HOME}/.digrc``. This file is read and any options in it are applied
before the command-line arguments. The :option:`-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 :option:`-t` and :option:`-c` options to specify the type and
class, use the :option:`-q` to specify the domain name, or use "IN." and
"CH." when looking up these top-level domains.

Simple Usage
~~~~~~~~~~~~

A typical invocation of :program:`dig` looks like:

::

    dig @server name type

where:

.. option:: 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, :program:`dig` resolves that name before querying that name
   server.

   If no ``server`` argument is provided, :program:`dig` consults
   ``/etc/resolv.conf``; if an address is found there, it queries the
   name server at that address. If either of the :option:`-4` or :option:`-6`
   options are in use, then only addresses for the corresponding
   transport are tried. If no usable addresses are found, :program:`dig`
   sends the query to the local host. The reply from the name server
   that responds is displayed.

.. option:: name

   is the name of the resource record that is to be looked up.

.. option:: 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, :program:`dig` performs a lookup for an A record.

Options
~~~~~~~

.. option:: -4

   This option indicates that only IPv4 should be used.

.. option:: -6

   This option indicates that only IPv6 should be used.

.. option:: -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``.

.. option:: -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.

.. option:: -f file

   This option sets batch mode, in which :program:`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 :program:`dig` using the
   command-line interface.

.. option:: -h

   Print a usage summary.

.. option:: -k keyfile

   This option tells :program:`dig` to sign queries using TSIG or
   SIG(0) using a key read from the given file. Key files can be
   generated using :iscman:`tsig-keygen`. When using TSIG authentication
   with :program:`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 :iscman:`named.conf` for TSIG and by looking up the KEY record
   in zone data for SIG(0).

.. option:: -m

   This option enables memory usage debugging.

.. option:: -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.

.. option:: -q name

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

.. option:: -r

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

.. option:: -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 :option:`-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`.

.. option:: -u

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

.. option:: -v

   This option prints the version number and exits.

.. option:: -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 :option:`-x` option is used, there is no
   need to provide the ``name``, ``class``, and ``type`` arguments.
   :program:`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.

.. option:: -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 :option:`-k` option should be used, rather than the :option:`-y` option,
   because with :option:`-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
~~~~~~~~~~~~~

:program:`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, :option:`+cd` is equivalent to
:option:`+cdflag`. The query options are:

.. option:: +aaflag, +noaaflag

   This option is a synonym for :option:`+aaonly`, :option:`+noaaonly`.

.. option:: +aaonly, +noaaonly

   This option sets the ``aa`` flag in the query.

.. option:: +additional, +noadditional

   This option displays [or does not display] the additional section of a reply. The
   default is to display it.

.. option:: +adflag, +noadflag

   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.

.. option:: +all, +noall

   This option sets or clears all display flags.

.. option:: +answer, +noanswer

   This option displays [or does not display] the answer section of a reply. The default
   is to display it.

.. option:: +authority, +noauthority

   This option displays [or does not display] the authority section of a reply. The
   default is to display it.

.. option:: +badcookie, +nobadcookie

   This option retries the lookup with a new server cookie if a BADCOOKIE response is
   received.

.. option:: +besteffort, +nobesteffort

   This option attempts to display the contents of messages which are malformed. The
   default is to not display malformed answers.

.. option:: +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`` restores the default buffer size.

.. option:: +cd, +cdflag, +nocdflag

   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.

.. option:: +class, +noclass

   This option displays [or does not display] the CLASS when printing the record.

.. option:: +cmd, +nocmd

   This option toggles the printing of the initial comment in the output, identifying the
   version of :program:`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.

.. option:: +coflag, +co, +nocoflag, +noco

   This option sets [or does not set] the CO (Compact denial of
   existence Ok) EDNS bit in the query.  If set, it tells servers
   that Compact Denial of Existence responses are acceptable when
   replying to queries.  The default is ``+nocoflag``.

.. option:: +comments, +nocomments

   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
   :option:`+cmd`, :option:`+question`, :option:`+stats`, and :option:`+rrcomments`.

.. option:: +cookie=####, +nocookie

   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 :option:`+trace` is set to better emulate the
   default queries from a nameserver.

.. option:: +crypto, +nocrypto

   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 ]``.

.. option:: +defname, +nodefname

   This option, which is deprecated, is treated as a synonym for
   :option:`+search`, :option:`+nosearch`.

.. option:: +dns64prefix, +nodns64prefix

   Lookup IPV4ONLY.ARPA AAAA and print any DNS64 prefixes found.

.. option:: +dnssec, +do, +nodnssec, +nodo

   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.

.. option:: +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 :option:`+search` option were
   given.

.. option:: +edns[=#], +noedns

   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.

.. option:: +ednsflags[=#], +noednsflags

   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, CO) is silently ignored. By default, no Z bits are set.

.. option:: +ednsnegotiation, +noednsnegotiation

   This option enables/disables EDNS version negotiation. By default, EDNS version
   negotiation is enabled.

.. option:: +ednsopt[=code[:value]], +noednsopt

   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.

.. option:: +expire, +noexpire

   This option sends an EDNS Expire option.

.. option:: +fail, +nofail

   This option indicates that :iscman:`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.

.. option:: +fuzztime[=value], +nofuzztime

   This option allows the signing time to be specified when generating
   signed messages.  If a value is specified it is the seconds since
   00:00:00 January 1, 1970 UTC ignoring leap seconds.  If no value
   is specified 1646972129 (Fri 11 Mar 2022 04:15:29 UTC) is used.
   The default is ``+nofuzztime`` and the current time is used.

.. option:: +header-only, +noheader-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.

.. option:: +https[=value], +nohttps

   This option indicates whether to use DNS over HTTPS (DoH) when querying
   name servers.  When this option is in use, the port number defaults to 443.
   The HTTP POST request mode is used when sending the query.

   If ``value`` is specified, it will be used as the HTTP endpoint in the
   query URI; the default is ``/dns-query``. So, for example, ``dig
   @example.com +https`` will use the URI ``https://example.com/dns-query``.

.. option:: +https-get[=value], +nohttps-get

   Similar to :option:`+https`, except that the HTTP GET request mode is used
   when sending the query.

.. option:: +https-post[=value], +nohttps-post

   Same as :option:`+https`.

.. option:: +http-plain[=value], +nohttp-plain

   Similar to :option:`+https`, except that HTTP queries will be sent over a
   non-encrypted channel. When this option is in use, the port number
   defaults to 80 and the HTTP request mode is POST.

.. option:: +http-plain-get[=value], +nohttp-plain-get

   Similar to :option:`+http-plain`, except that the HTTP request mode is GET.

.. option:: +http-plain-post[=value], +nohttp-plain-post

   Same as :option:`+http-plain`.

.. option:: +identify, +noidentify

   This option shows [or does not show] the IP address and port number that
   supplied the answer, when the :option:`+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.

.. option:: +idn, +noidn

   Enable or disable IDN processing. By default IDN is enabled for
   input query names, and for display when the output is a terminal.

   You can also turn off :program:`dig`'s IDN processing by setting
   the ``IDN_DISABLE`` environment variable.

.. option:: +ignore, +noignore

   This option ignores [or does not ignore] truncation in UDP
   responses instead of retrying with TCP. By default, TCP retries are
   performed.

.. option:: +keepalive, +nokeepalive

   This option sends [or does not send] an EDNS Keepalive option.

.. option:: +keepopen, +nokeepopen

   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``.

.. option:: +multiline, +nomultiline

   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 :program:`dig` output.

.. option:: +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
   :option:`+search` is set.

.. option:: +nsid, +nonsid

   When enabled, this option includes an EDNS name server ID request when sending a query.

.. option:: +nssearch, +nonssearch

   When this option is set, :program:`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.

.. option:: +onesoa, +noonesoa

   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.

.. option:: +opcode=value, +noopcode

   When enabled, this option sets (restores) the DNS message opcode to the specified value. The
   default value is QUERY (0).

.. option:: +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.

.. option:: +proxy[=src_addr[#src_port]-dst_addr[#dst_port]], +noproxy

   When this option is set, :program:`dig` adds PROXYv2 headers to the
   queries. When source and destination addresses are specified, the
   headers contain them and use the ``PROXY`` command. It means for
   the remote peer that the queries were sent on behalf of another
   node and that the PROXYv2 header reflects the original connection
   endpoints. The default source port is ``0`` and destination port is
   `53`.

   For encrypted DNS transports, to prevent accidental information
   leakage, encryption is applied to the PROXYv2 headers: the headers
   are sent right after the handshake process has been completed.

   For plain DNS transports, no encryption is applied to the PROXYv2
   headers.

   If the addressees are omitted, PROXYv2 headers, that use the
   ``LOCAL`` command set, are added instead. For the remote peer, that
   means that the queries were sent on purpose without being relayed,
   so the real connection endpoint addresses must be used.

.. option:: +proxy-plain[=src_addr[#src_port]-dst_addr[#dst_port], +noproxy-plain

   The same as ``+[no]proxy``, but instructs ``dig`` to send PROXYv2
   headers ahead of any encryption, before any handshake messages are
   sent. That makes :program:`dig` behave exactly how it is described
   in the PROXY protocol specification, but not all software expects
   such behaviour.

   Please consult the software documentation to find out if you need
   this option. (for example, ``dnsdist`` expects encrypted PROXYv2
   headers sent over TLS when encryption is used, while ``HAProxy``
   and many other software packages expect plain ones).

   For plain DNS transports the option is effectively an alias for the
   ``+[no]proxy`` described above.

.. option:: +qid=value

   This option specifies the query ID to use when sending queries.

.. option:: +qr, +noqr

   This option toggles the display of the query message as it is sent. By default, the query
   is not printed.

.. option:: +question, +noquestion

   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.

.. option:: +raflag, +noraflag

   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.

.. option:: +rdflag, +nordflag

   This option is a synonym for :option:`+recurse`, :option:`+norecurse`.

.. option:: +recurse, +norecurse

   This option toggles the setting of the RD (recursion desired) bit in the query.
   This bit is set by default, which means :program:`dig` normally sends
   recursive queries. Recursion is automatically disabled when the
   :option:`+nssearch` or :option:`+trace` query option is used.

.. option:: +retry=T

   This option sets the number of times to retry UDP and TCP queries to server to ``T``
   instead of the default, 2.  Unlike :option:`+tries`, this does not include
   the initial query.

.. option:: +rrcomments, +norrcomments

   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.

.. option:: +search, +nosearch

   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
   :option:`+ndots`, determines whether the name is treated as relative
   and hence whether a search is eventually performed.

.. option:: +short, +noshort

   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.

.. option:: +showbadcookie, +noshowbadcookie

   This option toggles whether to show the message containing the
   BADCOOKIE rcode before retrying the request or not. The default
   is to not show the messages.

.. option:: +showbadvers, +noshowbadvers

   This option toggles whether to show the message containing the
   BADVERS rcode before retrying the request or not. The default
   is to not show the messages.

.. option:: +showsearch, +noshowsearch

   This option performs [or does not perform] a search showing intermediate results.

.. option:: +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.

.. option:: +stats, +nostats

   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.

.. option:: +subnet=addr[/prefix-length], +nosubnet

   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.

.. option:: +tcflag, +notcflag

   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.

.. option:: +tcp, +notcp

   This option indicates whether to 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. To prevent retry over TCP when
   TC=1 is returned from a UDP query, use ``+ignore``.

.. option:: +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.

.. option:: +tls, +notls

   This option indicates whether to use DNS over TLS (DoT) when querying
   name servers. When this option is in use, the port number defaults
   to 853.

.. option:: +tls-ca[=file-name], +notls-ca

   This option enables remote server TLS certificate validation for
   DNS transports, relying on TLS. Certificate authorities
   certificates are loaded from the specified PEM file
   (``file-name``). If the file is not specified, the default
   certificates from the global certificates store are used.

.. option:: +tls-certfile=file-name, +tls-keyfile=file-name, +notls-certfile, +notls-keyfile

   These options set the state of certificate-based client
   authentication for DNS transports, relying on TLS. Both certificate
   chain file and private key file are expected to be in PEM format.
   Both options must be specified at the same time.

.. option:: +tls-hostname=hostname, +notls-hostname

   This option makes :program:`dig` use the provided hostname during remote
   server TLS certificate verification. Otherwise, the DNS server name
   is used. This option has no effect if :option:`+tls-ca` is not specified.

.. option:: +trace, +notrace

   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, :program:`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.

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

   Note that the ``delv +ns`` option can also be used for tracing the
   resolution of a name from the root (see :iscman:`delv`).

.. option:: +tries=T

   This option sets the number of times to try UDP and TCP 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.

.. option:: +ttlid, +nottlid

   This option displays [or does not display] the TTL when printing the record.

.. option:: +ttlunits, +nottlunits

   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 :option:`+ttlid`.

.. option:: +unknownformat, +nounknownformat

   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.

.. option:: +vc, +novc

   This option uses [or does not use] TCP when querying name servers. This alternate
   syntax to :option:`+tcp` is provided for backwards compatibility. The
   ``vc`` stands for "virtual circuit."

.. option:: +yaml, +noyaml

   When enabled, this option prints the responses (and, if :option:`+qr` is in use, also the
   outgoing queries) in a detailed YAML format.

.. option:: +zflag, +nozflag

   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 :program:`dig` supports specifying multiple
queries on the command line (in addition to supporting the :option:`-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 :option:`+cmd` and
:option:`+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 :program:`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
:option:`+qr` is applied, so that :program:`dig` shows the initial query it made for
each lookup. The final query has a local query option of :option:`+noqr` which
means that :program:`dig` does not print the initial query when it looks up the
NS records for ``isc.org``.

Return Codes
~~~~~~~~~~~~

:program:`dig` return codes are:

``0``
   DNS response received, including NXDOMAIN status

``1``
   Usage error

``8``
   Couldn't open batch file

``9``
   No reply from server

``10``
   Internal error

Files
~~~~~

``/etc/resolv.conf``

``${HOME}/.digrc``

See Also
~~~~~~~~

:iscman:`delv(1) <delv>`, :iscman:`host(1) <host>`, :iscman:`named(8) <named>`, :iscman:`dnssec-keygen(8) <dnssec-keygen>`, :rfc:`1035`.

Bugs
~~~~

There are probably too many query options.