DIG (1)

send domain name query packets to name servers

SYNOPSIS

dig Ic @ Ns Ar server domain Aq Ar query-type Aq Ar query-class Ic + Ns Aq Ar query-option Fl Aq Ar dig-option Ar %comment

DESCRIPTION

Dig (domain information groper) is a flexible command line tool which can be used to gather information from the Domain Name System servers. Dig has two modes: simple interactive mode for a single query, and batch mode which executes a query for each in a list of several query lines. All query options are accessible from the command line.

The usual simple use of dig will take the form:

-ragged -offset indent-two dig @ Ns Ar server domain query-type query-class

where: -tag -width Fl

Ar server may be either a domain name or a dot-notation Internet address. If this optional field is omitted, dig will attempt to use the default name server for your machine. Note: If a domain name is specified, this will be resolved using the domain name system resolver (i.e., BIND). If your system does not support DNS, you may have to specify a dot-notation address. Alternatively, if there is a server at your disposal somewhere, all that is required is that /etc/resolv.conf be present and indicate where the default name servers reside, so that server itself can be resolved. See resolver 5 for information on /etc/resolv.conf . WARNING: Changing /etc/resolv.conf will affect both the standard resolver library and potentially several programs which use it. As an option, the user may set the environment variable LOCALRES to name a file which is to be used instead of /etc/resolv.conf Ns Ev LOCALRES is specific to the dig resolver and is not referenced by the standard resolver . If the LOCALRES variable is not set or the specified file is not readable, then /etc/resolv.conf will be used.

Ar domain is the domain name for which you are requesting information. See the x option (documented in the OTHER OPTIONS subsection of this section) for convenient way to specify inverse address query.

Ar query-type is the type of information (DNS query type) that you are requesting. If omitted, the default is Ar a Dv T_A = Ar address . The following types are recognized:

-hang -width "hinfo T_HINFO " -compact

Ar a\ \ \ \ \ \ Dv T_A network address

Ar any\ \ \ \ Dv T_ANY all/any information about specified domain

Ar mx\ \ \ \ \ Dv T_MX mail exchanger for the domain

Ar ns\ \ \ \ \ Dv T_NS name servers

Ar soa\ \ \ \ Dv T_SOA zone of authority record

Ar hinfo\ \ Dv T_HINFO host information

Ar axfr\ \ \ Dv T_AXFR zone transfer (must ask an authoritative server)

Ar txt\ \ \ \ Dv T_TXT arbitrary number of strings

(See RFC 1035 for the complete list.)

Ar query-class is the network class requested in the query. If omitted, the default is Ar in Dv C_IN = Ar Internet . The following classes are recognized:

-tag -width "hinfo T_HINFO " -compact

Ar in\ \ \ \ \ Dv C_IN Internet class domain

Ar any\ \ \ \ Dv C_ANY all/any class information

(See RFC 1035 for the complete list.)

Note: Ar Any can be used to specify a class and/or a type of query. Dig will parse the first occurrence of Ar any to mean query-type = Dv T_ANY . To specify query-class = Dv C_ANY , you must either specify any twice, or set query-class using the c option (see below). -tag -width Fl

% Ns Ar ignored-comment % is used to included an argument that is simply not parsed. This may be useful if running dig in batch mode. Instead of resolving every @server-domain-name in a list of queries, you can avoid the overhead of doing so, and still have the domain name on the command line as a reference. Example:

-ragged -offset indent-two dig @128.9.0.32 %venera.isi.edu mx isi.edu

Fl Aq Ar dig option Fl is used to specify an option which affects the operation of dig . The following options are currently available (although not guaranteed to be useful): -tag -width Fl

Fl x Ar dot-notation-address Convenient form to specify inverse address mapping. Instead of Ic dig 32.0.9.128.in-addr.arpa , one can simply Ic dig -x 128.9.0.32 .

Fl f Ar file File for dig batch mode. The file contains a list of query specifications ( Ic dig command lines) which are to be executed successively. Lines beginning with ; , # , or \en are ignored. Other options may still appear on command line, and will be in effect for each batch query.

Fl T Ar time Time in seconds between start of successive queries when running in batch mode. Can be used to keep two or more batch dig commands running roughly in sync. Default is zero.

Fl p Ar port Port number. Query a name server listening to a non-standard port number. Default is 53.

Fl P Ns Bq Ar ping-string After query returns, execute a ping 8 command for response time comparison. This rather unelegantly makes a call to the shell. The last three lines of statistics is printed for the command:

-ragged -offset indent-two ping Fl s server_name 56 3

If the optional Ar ping_string is present, it replaces Ic ping Fl s in the shell command.

Fl t Ar query-type Specify type of query. May specify either an integer value to be included in the type field or use the abbreviated mnemonic as discussed above (i.e., mx = Dv T_MX ) .

Fl c Ar query-class Specify class of query. May specify either an integer value to be included in the class field or use the abbreviated mnemonic as discussed above (i.e., in = C_IN).

Fl envsav This flag specifies that the dig environment (defaults, print options, etc.), after all of the arguments are parsed, should be saved to a file to become the default environment. This is useful if you do not like the standard set of defaults and do not desire to include a large number of options each time dig is used. The environment consists of resolver state variable flags, timeout, and retries as well as the flags detailing dig output (see below). If the shell environment variable LOCALDEF is set to the name of a file, this is where the default dig environment is saved. If not, the file Pa DiG.env is created in the current working directory.

Note: LOCALDEF is specific to the dig resolver, and will not affect operation of the standard resolver library.

Each time dig is executed, it looks for Pa ./DiG.env or the file specified by the shell environment variable LOCALDEF . If such file exists and is readable, then the environment is restored from this file before any arguments are parsed.

Fl envset This flag only affects batch query runs. When Fl envset is specified on a line in a dig batch file, the dig environment after the arguments are parsed becomes the default environment for the duration of the batch file, or until the next line which specifies Fl envset .

Xo Op Cm no Cm stick This flag only affects batch query runs. It specifies that the dig environment (as read initially or set by Fl envset switch) is to be restored before each query (line) in a dig batch file. The default Fl nostick means that the dig environment does not stick, hence options specified on a single line in a dig batch file will remain in effect for subsequent lines (i.e. they are not restored to the sticky default).

+ Ns Aq Ar query-option + is used to specify an option to be changed in the query packet or to change dig output specifics. Many of these are the same parameters accepted by nslookup 8 . If an option requires a parameter, the form is as follows:

-ragged -offset indent-two + Ar keyword Op = Ns Ar value

Most keywords can be abbreviated. Parsing of the + options is very simplistic a value must not be separated from its keyword by white space. The following keywords are currently available:

Keyword Abbrev. Meaning [default]

-tag -width "[no]primary (ret) " -compact

Xo Cm no Cm debug\ \ \ \ Cm deb turn on/off debugging mode Cm deb

Xo Cm no Cm d2\ \ \ \ \ \ \ \ \ \ turn on/off extra debugging mode Cm nod2

Xo Cm no Cm recurse\ \ Cm rec use/don't use recursive lookup Cm rec

Xo retry= Ns Ar # \ \ \ \ \ Cm ret set number of retries to # 4

Xo time= Ns Ar # \ \ \ \ \ \ Cm ti set timeout length to # seconds 4

Xo Cm no Cm ko keep open option (implies vc) Cm noko

Xo Cm no Cm vc use/don't use virtual circuit Cm novc

Xo Cm no Cm defname\ \ Cm def use/don't use default domain name Cm def

Xo Cm no Cm search\ \ \ Cm sea use/don't use domain search list Cm sea

Xo domain= Ns Ar NAME\ \ Cm do set default domain name to NAME

Xo Cm no Cm ignore\ \ \ Cm i ignore/don't ignore trunc. errors Cm noi

Xo Cm no Cm primary\ \ Cm pr use/don't use primary server Cm nopr

Xo Cm no Cm aaonly\ \ \ Cm aa authoritative query only flag Cm noaa

Xo Cm no Cm cmd echo parsed arguments Cm cmd

Xo Cm no Cm stats\ \ \ \ Cm st print query statistics Cm st

Xo Cm no Cm Header\ \ \ Cm H print basic header Cm H

Xo Cm no Cm header\ \ \ Cm he print header flags Cm he

Xo Cm no Cm ttlid\ \ \ \ Cm tt print TTLs Cm tt

Xo Cm no Cm cl print class info Cm nocl

Xo Cm no Cm qr print outgoing query Cm noqr

Xo Cm no Cm reply\ \ \ \ Cm rep print reply Cm rep

Xo Cm no Cm ques\ \ \ \ \ Cm qu print question section Cm qu

Xo Cm no Cm answer\ \ \ Cm an print answer section Cm an

Xo Cm no Cm author\ \ \ Cm au print authoritative section Cm au

Xo Cm no Cm addit\ \ \ \ Cm ad print additional section Cm ad

Cm pfdef set to default print flags

Cm pfmin set to minimal default print flags

Cm pfset= Ns Ar # set print flags to # (# can be hex/octal/decimal)

Cm pfand= Ns Ar # bitwise and print flags with #

Cm pfor= Ns Ar # bitwise or print flags with #

The retry and time options affect the retransmission strategy used by the resolver library when sending datagram queries. The algorithm is as follows:

-literal -offset indent for i = 0 to retry - 1 for j = 1 to num_servers send_query wait((time * (2**i)) / num_servers) end end

(Note: dig always uses a value of 1 for Li num_servers . ) Dig once required a slightly modified version of the BIND resolver 3 library. As of BIND 4.9, BIND's resolver has been augmented to work properly with dig . Essentially, dig is a straight-forward (albeit not pretty) effort of parsing arguments and setting appropriate parameters. Dig uses resolver 3 routines res_init , res_mkquery , res_send as well as accessing the _res structure.

ENVIRONMENT

-tag -width "LOCALRES " -compact

Ev LOCALRES file to use in place of Pa /etc/resolv.conf

Ev LOCALDEF default environment file

See also the explanation of the envsav , envset , and Op Cm no Cm stick options, above.

FILES

-tag -width "/etc/resolv.conf " -compact

Pa /etc/resolv.conf initial domain name and name server addresses

Pa \./DiG.env default save file for default options

SEE ALSO

- named (8) - - resolver (3) - - resolver (5) - - nslookup (8) -

STANDARDS

RFC 1035.

AUTHOR

Steve Hotz hotz@isi.edu

ACKNOWLEDGMENTS

Dig uses functions from nslookup 8 authored by Andrew Cherenson.

BUGS

Dig has a serious case of "creeping featurism" -- the result of considering several potential uses during it's development. It would probably benefit from a rigorous diet. Similarly, the print flags and granularity of the items they specify make evident their rather ad hoc genesis.

Dig does not consistently exit nicely (with appropriate status) when a problem occurs somewhere in the resolver Sy NOTE: most of the common exit cases are handled . This is particularly annoying when running in batch mode. If it exits abnormally (and is not caught), the entire batch aborts; when such an event is trapped, dig simply continues with the next query.

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