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dig(1) OpenBSD Reference Manual dig(1)
dig - send domain name query packets to name servers
dig [@server] domain [query-type] [query-class] [-f file] [-T time] [-p
port] [-P[ping-string]] [-t query-type] [-c query-class] [-envsav]
[-envset] [-stick | -nostick] [+keyword[=value]] [%comment]
dig [@server] -x dot-notation-address [...]
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 which makes a single query, and
batch 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:
dig @server domain query-type query-class
server may be either a domain name or a dot-notation Internet ad-
dress. 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 resolv.conf(5) for information on /etc/resolv.conf.
Warning: Changing /etc/resolv.conf will affect 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 (LOCALRES is specific to the dig resolver
and not referenced by the standard resolver). If the
LOCALRES variable is not set or the file is not readable
then /etc/resolv.conf will be used.
domain is the domain name for which you are requesting information.
See OTHER OPTIONS (-x) for a convenient way to specify in-
verse address query.
query-type is the type of information (DNS query type) that you are re-
questing. If omitted, the default is ``a'' (T_A = address).
The following types are recognized:
a T_A network address
any T_ANY all/any information about specified domain
mx T_MX mail exchanger for the domain
ns T_NS name servers
soa T_SOA zone of authority record
hinfo T_HINFO host information
axfr T_AXFR zone transfer
(must ask an authoritative server)
txt T_TXT arbitrary number of strings
(See RFC 1035 for the complete list.)
query-class is the network class requested in the query. If omitted, the
default is ``in'' (C_IN = Internet). The following classes
in C_IN Internet class domain
any C_ANY all/any class information
(See RFC 1035 for the complete list.)
Note: ``any'' can be used to specify a class and/or a type
of query. dig will parse the first occurrence of ``any'' to
mean query-type = T_ANY. To specify query-class = C_ANY you
must either specify ``any'' twice, or set query-class using
-c option (see below).
``%'' 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.
dig @188.8.131.52 %venera.isi.edu mx isi.edu
Convenient form to specify inverse address mapping. In-
one can simply
dig -x 184.108.40.206
-f file File for dig batch mode. The file contains a list of query
specifications (dig command lines) which are to be executed
successively. Lines beginning with ';', '#', or '\n' are
ignored. Other options may still appear on command line,
and will be in effect for each batch query.
-T 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 ze-
-p port Port number. Query a name server listening to a non-stan-
dard port number. Default is 53.
After query returns, execute a ping(1) command for response
time comparison. This rather inelegantly makes a call to
the shell. The last three lines of statistics are printed
for the command:
ping -s server_name 56 3
If the optional ping-string is present, it replaces ``ping
-s'' in the shell command.
Specify the type of query. This may specify either an inte-
ger value to be included in the type field or use the ab-
breviated mnemonic as discussed above (i.e., mx = T_MX).
Specify the class of query. This may specify either an in-
teger value to be included in the class field or use the
abbreviated mnemonic as discussed above (i.e., in = C_IN).
-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 en-
vironment. Useful if you do not like the standard set of
defaults and do not desire to include a large number of op-
tions 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 DiG.env is created in the current working
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 DiG.env int the
working directory, or the file specified by the shell envi-
ronment variable LOCALDEF. If the file exists and is read-
able, then the environment is restored from it before any
arguments are parsed.
-envset This flag only affects batch query runs. When -envset is
specified on a line in a dig batch file, the dig environ-
ment after the arguments are parsed, becomes the default
environment for the duration of the batch file, or until
the next line which specifies -envset.
-stick | -nostick
These flags only affects batch query runs. -stick speci-
fies that the dig environment (as read initially or set by
-envset switch) is to be restored before each query (line)
in a dig batch file. The default -nostick means that the
dig environment does not stick; that is, 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
``+'' 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).
Most keywords can be abbreviated. Parsing of the ``+'' op-
tions is very simplistic -- a value must not be separated
from its keyword by white space. The following s are
Keyword Abbrev. Meaning [default]
[no]debug (deb) turn on/off debugging mode [deb]
[no]d2 turn on/off extra debugging mode [nod2]
[no]recurse (rec) use/don't use recursive lookup [rec]
retry=# (ret) set number of retries to # 
time=# (ti) set timeout length to # seconds 
[no]ko keep open option (implies vc) [noko]
[no]vc use/don't use virtual circuit [novc]
[no]defname (def) use/don't use default domain name [def]
[no]search (sea) use/don't use domain search list [sea]
domain=NAME (do) set default domain name to NAME
[no]ignore (i) ignore/don't ignore trunc. errors [noi]
[no]primary (pr) use/don't use primary server [nopr]
[no]aaonly (aa) authoritative query only flag [noaa]
[no]sort (sor) sort resource records [nosor]
[no]cmd echo parsed arguments [cmd]
[no]stats (st) print query statistics [st]
[no]Header (H) print basic header [H]
[no]header (he) print header flags [he]
[no]ttlid (tt) print TTLs [tt]
[no]cl print class info [nocl]
[no]qr print outgoing query [noqr]
[no]reply (rep) print reply [rep]
[no]ques (qu) print question section [qu]
[no]answer (an) print answer section [an]
[no]author (au) print authoritative section [au]
[no]addit (ad) print additional section [ad]
pfdef set to default print flags
pfmin set to minimal default print flags
pfset=# set print flags to #
(# can be hex/octal/decimal)
pfand=# bitwise and print flags with #
pfor=# bitwise or print flags with #
The keywordfile ... and time keywords affect the retrans-
mission strategy used by resolver library when sending
datagram queries. The algorithm is as follows:
for i = 0 to retry - 1
for j = 1 to num_servers
wait((time * (2**i)) / num_servers)
Note: dig always uses a value of 1 for num_servers.
dig once required a slightly modified version of the BIND resolver(3) li-
brary. BIND's resolver has (as of BIND 4.9) been augmented to work prop-
erly with dig. Essentially, dig is a straight-forward (albeit not pretty)
effort of parsing arguments and setting appropriate parameters. dig uses
resolver routines res_init(), res_mkquery(), res_send() as well as ac-
cessing the _res structure.
/etc/resolv.conf initial domain name and name
DiG.env default save file for default op-
LOCALRES file to use in place of /etc/resolv.conf
LOCALDEF default environment file
Steve Hotz email@example.com
dig uses functions from nslookup(8) authored by Andrew Cherenson.
dig has a serious case of ``creeping featurism'' -- the result of consid-
ering 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. (Note: most of the common exit
cases are handled). This is particularly annoying when running in batch
mode. If the resolver exits abnormally (and is not caught), the entire
batch aborts; when such an event is trapped, dig simply continues with
the next query.
resolver(3), resolv.conf(5), named(8), nslookup(8)
OpenBSD 2.6 August 30, 1990 5
Source: OpenBSD 2.6 man pages. Copyright: Portions are copyrighted by BERKELEY
SOFTWARE DESIGN, INC., The Regents of the University of California, Massachusetts
Institute of Technology, Free Software Foundation, FreeBSD Inc., and others.
(Corrections, notes, and links courtesy of RocketAware.com)
FreeBSD Sources for dig(1)
OpenBSD sources for dig(1)
Up to: Host, service name, and address operations - Methods and functions for doing address, host, user, and service name lookups (DNS). also Internet Assigned Numbers
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