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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. 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. If no usable server addresses are found, dig will send the query to
       the local host.

       When no command line arguments or options are given, dig 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 domain names. Either use
       the -t and -c options to specify the type and class, 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
           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 will be tried.
           If no usable addresses are found, dig will send 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 will perform a lookup for an A
           record.

OPTIONS

       -4
           Use IPv4 only.

       -6
           Use IPv6 only.

       -b address[#port]
           Set 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
           Set the query class. The default class is IN; other classes are HS for Hesiod records
           or CH for Chaosnet records.

       -f file
           Batch mode: 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 they would be presented as
           queries to dig using the command-line interface.

       -i
           Do reverse IPv6 lookups using the obsolete RFC 1886 IP6.INT domain, which is no longer
           in use. Obsolete bit string label queries (RFC 2874) are not attempted.

       -k keyfile
           Sign queries using TSIG using a key read from the given file. Key files can be
           generated using tsig-keygen(8). 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
           Enable memory usage debugging.

       -p port
           Send the query to a non-standard port on the server, instead of the default port 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.

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

       -t type
           The resource record type to query. It 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 will contain the 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 will be
           displayed as described in RFC 3597.

       -u
           Print query times in microseconds instead of milliseconds.

       -v
           Print the version number and exit.

       -x addr
           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 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 (but see also the -i option).

       -y [hmac:]keyname:secret
           Sign 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 or if
           MD5 was disabled hmac-sha256.

           NOTE: You should use the -k option and avoid 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 ps(1) 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
           A synonym for +[no]aaonly.

       +[no]aaonly
           Sets the "aa" flag in the query.

       +[no]additional
           Display [do not display] the additional section of a reply. The default is to display
           it.

       +[no]adflag
           Set [do 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 all 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
           indicate that some part of the answer was insecure or not validated. This bit is set
           by default.

       +[no]all
           Set or clear all display flags.

       +[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]badcookie
           Retry lookup with the new server cookie if a BADCOOKIE response is received.

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

       +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.

       +[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]class
           Display [do not display] the CLASS when printing the record.

       +[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]comments
           Toggle the display of comment lines in the output. The default is to print comments.

       +[no]cookie[=####]
           Send a COOKIE EDNS option, with optional value. Replaying a COOKIE from a previous
           response will allow 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
           Toggle the display of cryptographic fields in DNSSEC records. The contents of these
           field are unnecessary to debug 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
           Deprecated, treated as a synonym for +[no]search

       +[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.

       +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.

       +dscp=value
           Set 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[=#]
           Specify the EDNS version to query with. Valid values are 0 to 255. Setting the EDNS
           version will cause a EDNS query to be sent.  +noedns clears the remembered EDNS
           version. EDNS is set to 0 by default.

       +[no]ednsflags[=#]
           Set 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) will silently be ignored.
           By default, no Z bits are set.

       +[no]ednsnegotiation
           Enable / disable EDNS version negotiation. By default EDNS version negotiation is
           enabled.

       +[no]ednsopt[=code[:value]]
           Specify EDNS option with code point code and optionally 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
           Send an EDNS Expire option.

       +[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]header-only
           Send 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
           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]idnin
           Process [do 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.

       +[no]idnout
           Convert [do not convert] puny code on output. This requires IDN SUPPORT to have been
           enabled at compile time. The default is to convert output.

       +[no]ignore
           Ignore truncation in UDP responses instead of retrying with TCP. By default, TCP
           retries are performed.

       +[no]keepopen
           Keep the TCP socket open between queries and reuse it rather than creating a new TCP
           socket for each lookup. The default is +nokeepopen.

       +[no]mapped
           Allow mapped IPv4 over IPv6 addresses to be used. The default is +mapped.

       +[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.

       +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 if +search is set.

       +[no]nsid
           Include 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.

       +[no]onesoa
           Print only one (starting) SOA record when performing an AXFR. The default is to print
           both the starting and ending SOA records.

       +[no]opcode=value
           Set [restore] the DNS message opcode to the specified value. The default value is
           QUERY (0).

       +[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]rdflag
           A synonym for +[no]recurse.

       +[no]recurse
           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.

       +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.

       +[no]rrcomments
           Toggle 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
           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.

           'ndots' from resolv.conf (default 1) which may be overridden by +ndots determines if
           the name will be treated as relative or not and hence whether a search is eventually
           performed or not.

       +[no]short
           Provide a terse answer. The default is to print the answer in a verbose form.

       +[no]showsearch
           Perform [do not perform] a search showing intermediate results.

       +[no]sigchase
           Chase DNSSEC signature chains. Requires dig be compiled with -DDIG_SIGCHASE. This
           feature is deprecated. Use delv instead.

       +split=W
           Split 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 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]subnet=addr[/prefix-length]
           Send (don't 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]tcp
           Use [do 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
           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.

       +[no]topdown
           When chasing DNSSEC signature chains perform a top-down validation. Requires dig be
           compiled with -DDIG_SIGCHASE. This feature is deprecated. Use delv instead.

       +[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.

           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
           nameserver.

       +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.

       +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. This feature is deprecated. Use delv
           instead.

       +[no]ttlid
           Display [do not display] the TTL when printing the record.

       +[no]ttlunits
           Display [do not display] the TTL in friendly human-readable time units of "s", "m",
           "h", "d", and "w", representing seconds, minutes, hours, days and weeks. Implies
           +ttlid.

       +[no]unknownformat
           Print 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
           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]zflag
           Set [do 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 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.

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, use parameters +noidnin and
       +noidnout.

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, Inc.

COPYRIGHT

       Copyright © 2000-2011, 2013-2018 Internet Systems Consortium, Inc. ("ISC")