DIG(1)DIG(1)NAMEdig - send domain name query packets to name servers
SYNOPSISdig [@server] domain [<query-type>] [<query-class>] [+<query-option>]
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 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 infor‐
mation on /etc/resolv.conf. (WARNING: Changing /etc/resolv.conf
will affect the standard resolver library and potentially sev‐
eral 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 OPTIONS [-x] for convenient way to specify inverse address
is the type of information (DNS query type) that you are
requesting. 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.)
is the network class requested in the query. If omitted, the
default is "in" (C_IN = Internet). The following classes are
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
"%" 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:
dig @18.104.22.168 %venera.isi.edu mx isi.edu
"-" is used to specify an option which effects the operation of
dig. The following options are currently available (although not
guaranteed to be useful):
Convenient form to specify inverse address mapping.
Instead of "dig 22.214.171.124.in-addr.arpa" one can simply
"dig -x 126.96.36.199".
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 com‐
mand line, and will be in effect for each batch query.
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
Port number. Query a name server listening to a non-stan‐
dard port number. Default is 53.
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:
ping -s server_name 56 3
If the optional "ping string" is present, it replaces
"ping -s" in the shell command.
Specify type of query. May specify either an integer
value to be included in the type field or use the abbre‐
viated mnemonic as discussed above (i.e., mx = T_MX).
Specify class of query. May specify either an integer
value to be included in the class field or use the abbre‐
viated mnemonic as discussed above (i.e., in = C_IN).
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. 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 con‐
sists 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 cre‐
ated 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 "./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 argu‐
ments are parsed.
This flag only affects batch query runs. When "-envset"
is specified on a line in a dig batch file, the dig envi‐
ronment after the arguments are parsed, becomes the
default environment for the duration of the batch file,
or until the next line which specifies "-envset".
This flag only affects batch query runs. It specifies
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, 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).
"+" 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(1). If an option requires
a parameter, the form is as follows:
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
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 retry and time options affect the retransmission 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)
library. BIND's resolver has (as of BIND 4.9) 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 routines res_init(), res_mkquery(), res_send() as
well as accessing _res structure.
/etc/resolv.conf initial domain name and name server
LOCALRES file to use in place of /etc/resolv.conf
LOCALDEF default environment file
Steve Hotz firstname.lastname@example.org
Dig uses functions from nslookup(1) 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 proba‐
bly benefit from a rigorous diet. Similarly, the print flags and gran‐
ularity of the items they specify make evident their rather ad hoc gen‐
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 it exits abnormally (and is not caught), the entire
batch aborts; when such an event is trapped, dig simply continues with
the next query.
SEE ALSOnamed(8), resolver(3), resolver(5), nslookup(1)
August 30, 1990 DIG(1)