dig
DIG(1) System General Commands Manual DIG(1)
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 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:
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 resolver(5) for information on /etc/resolv.conf.
WARNING: Changing /etc/resolv.conf will affect both the stan
dard 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 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.
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.
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
the -c option (see below).
OTHER OPTIONS
%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:
dig @128.9.0.32 %venera.isi.edu mx isi.edu
-<dig option>
``-'' is used to specify an option which affects the opera
tion of dig. The following options are currently available
(although not guaranteed to be useful):
-x dot-notation-address
Convenient form to specify inverse address map
ping. 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 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 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(8) command
for response time comparison. This rather unele
gantly 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.
-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).
-k keydir:keyname
Sign the query with the TSIG key named keyname
that is in the directory keydir.
-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 use
ful 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 environ
ment 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 after the arguments are
parsed becomes 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 ini
tially 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(8). 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 toNAME
[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] 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 the 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''.)
DETAILS
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
LOCALRES file to use in place of Pa /etc/resolv.conf
LOCALDEF default environment file
See also the explanation of the -envsav, -envset, and -[no] stick
options, above.
FILES
/etc/resolv.conf
initial domain name and name server addresses
./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 consider
ing 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.
4th Berkeley Distribution August 30, 1990 4th Berkeley Distribution