Provided by: bind9-dnsutils_9.18.28-0ubuntu0.22.04.1_amd64 bug

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.

       -h     Print a usage summary.

       -k keyfile
              This option tells dig to sign queries using TSIG or SIG(0) 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 for TSIG and by looking up the  KEY  record  in
              zone data for SIG(0).

       -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:

       +aaflag, +noaaflag
              This option is a synonym for +aaonly, +noaaonly.

       +aaonly, +noaaonly
              This option sets the aa flag in the query.

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

       +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.

       +all, +noall
              This option sets or clears all display flags.

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

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

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

       +besteffort, +nobesteffort
              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 restores the default buffer size.

       +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.

       +class, +noclass
              This option displays [or does not display] the CLASS when printing the record.

       +cmd, +nocmd
              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.

       +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  +cmd,  +question,
              +stats, and +rrcomments.

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

       +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 ].

       +defname, +nodefname
              This option, which is deprecated, is treated as a synonym for +search, +nosearch.

       +dns64prefix, +nodns64prefix
              Lookup IPV4ONLY.ARPA AAAA and print any DNS64 prefixes found.

       +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.

       +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 formerly set the DSCP value used when  sending  a  query.   It  is  now
              obsolete, and has no effect.

       +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.

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

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

       +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.

       +expire, +noexpire
              This option sends an EDNS Expire option.

       +fail, +nofail
              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.

       +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.

       +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.

       +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.

       +https-get[=value], +nohttps-get
              Similar to +https, except that the HTTP GET request mode is used when  sending  the
              query.

       +https-post[=value], +nohttps-post
              Same as +https.

       +http-plain[=value], +nohttp-plain
              Similar  to  +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.

       +http-plain-get[=value], +nohttp-plain-get
              Similar to +http-plain, except that the HTTP request mode is GET.

       +http-plain-post[=value], +nohttp-plain-post
              Same as +http-plain.

       +identify, +noidentify
              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.

       +idnin, +noidnin
              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.

       +idnout, +noidnout
              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.

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

       +keepalive, +nokeepalive
              This option sends [or does not send] an EDNS Keepalive 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.

       +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 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.

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

       +nssearch, +nonssearch
              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.

       +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.

       +opcode=value, +noopcode
              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.

       +qid=value
              This option specifies the query ID to use when sending queries.

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

       +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.

       +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.

       +rdflag, +nordflag
              This option is a synonym for +recurse, +norecurse.

       +recurse, +norecurse
              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 and TCP queries to  server  to  T
              instead of the default, 2.  Unlike +tries, this does not include the initial query.

       +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.

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

       +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.

       +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.

       +showsearch, +noshowsearch
              This option performs [or does not perform] a search showing intermediate results.

       +sigchase, +nosigchase
              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.

       +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.

       +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.

       +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.

       +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.

       +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.

       +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.

       +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.

       +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.

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

       +topdown, +notopdown
              This  feature  is related to dig +sigchase, which is obsolete and has been removed.
              Use delv instead.

       +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,
              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 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.

       +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.

       +ttlid, +nottlid
              This option displays [or does not display] the TTL when printing the record.

       +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 +ttlid.

       +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.

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

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

       +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 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 +cmd and +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 +idnin and +idnout,  or  define  the  IDN_DISABLE
       environment variable.

RETURN CODES

       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

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

BUGS

       There are probably too many query options.

AUTHOR

       Internet Systems Consortium

COPYRIGHT

       2024, Internet Systems Consortium