dig(1M) TCP/IP R4.11 dig(1M)
NAME
dig - send domain name query packets to name servers
SYNOPSIS
dig [@server] domain [query-type] [query-class] [+query-option]
[-dig-option] [%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, which makes 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:
dig @server domain query-type query-class
where:
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 resolv.conf(4M) 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 OPTIONS [-x] for a convenient way to specify inverse
address query.
query-type
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.)
query-class
is the network class requested in the query. If omitted, the
default is "in" (C_IN = Internet). The following classes are
recognized:
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).
OTHER OPTIONS
%ignored-comment
"%" is used to include 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 @128.9.0.32 %venera.isi.edu mx isi.edu
-<dig option>
"-" is used to specify an option which affects the operation
of dig. The following options are currently available
(although not guaranteed to be useful):
-x dot-notation-address
Convenient form to specify inverse address mapping.
Instead of "dig 32.0.9.128.in-addr.arpa" one can simply
"dig -x 128.9.0.32".
-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 lines 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 zero.
-p port
Port number. Query a name server listening to a non-
standard port number. Default is 53.
-P[ping-string]
After query returns, execute a ping(1M) command for
response time comparison. This rather unelegantly makes
a call to the shell. The last three lines of statistics
are printed for the command:
ping -s -c 3 server_name 56
If the optional "ping string" is present, it replaces
"ping -s" in the shell command.
-t 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 =
T_MX).
-c 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).
-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. 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
"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 "./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.
-envset
This flag only affects batch query runs. When "-envset"
is specified on a line in a dig batch file, the dig
environment will, after the arguments are parsed,
become the default environment for the duration of the
batch file or until the next line which specifies
"-envset".
-[no]stick
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).
+<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(1M). If an option
requires a parameter, the form is as follows:
+keyword[=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]
[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 # [4]
time=# (ti) set timeout length to # seconds [4]
[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
send_query
wait((time * (2**i)) / num_servers)
end
end
(Note: dig always uses a value of 1 for num_servers.)
FILES
/etc/resolv.conf initial domain name and name server
DiG.env default save file for default options
ENVIRONMENT
LOCALRES file to use in place of /etc/resolv.conf
LOCALDEF default environment file
AUTHOR
Steve Hotz hotz@isi.edu
ACKNOWLEDGMENTS
Dig uses functions from nslookup(1M) authored by Andrew Cherenson.
NOTES
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 (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 ALSO
named(1M), resolver(3C), resolv.conf(4M), nslookup(1M), dnsquery(1M),
host(1M).
Licensed material--property of copyright holder(s)