DIG(1) BSD Reference 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 raw (IPv4 /
IPv6) 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 re-
solver library and (potentially) several pro-
grams which use
it. As an option, the user may set the environ-
ment variable
LOCALRES to name a file which is to be used in-
stead of
/etc/resolv.conf standard resolver (LOCALRESis
specific to
the dig resolver and is not referenced by
the). 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
reverse ad-
dress 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 follow-
ing 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. Ex-
ample:
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
32.0.9.28.in-addr.arpa'',
one can simply ``dig -x 28.9.0.32''.
-x IPv6-address
Convenient form to specify inverse
address map-
ping. Instead of ``dig
1.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa'',
one can simply ``dig -x ::1''.
-f file File for dig batch mode. The file
contains a list
of query specifications ( dig com-
mand lines)
which are to be executed successive-
ly. Lines be-
ginning with `;', `#', or `0 are ig-
nored. Oth-
er options may still appear on com-
mand 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 com-
mands 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 in-
teger value to be included in the
type field or
use the abbreviated mnemonic as dis-
cussed above
(i.e., mx = T_MX).
-c query-class
Specify class of query. May specify
either an in-
teger value to be included in the
class field or
use the abbreviated mnemonic as dis-
cussed 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 en-
vironment (de-
faults, 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 de-
faults and do not desire to include
a large num-
ber of options each time dig is
used. The envi-
ronment 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 di-
rectory.
Note: LOCALDEF is specific to the
dig resolver,
and will not affect operation of the
standard re-
solver library.
Each time dig is executed, it looks
for
``./DiG.env'' or the file specified
by the shell
environment variable LOCALDEF. If
such file ex-
ists and is readable, then the envi-
ronment is re-
stored from this file before any ar-
guments 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 environ-
ment 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 re-
stored 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 ``+'' op-
tions 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 debug-
ging 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 (im-
plies 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] 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] trunc (tr) truncate origin from
names [tr]
[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 sec-
tion [au]
[no] addit (ad) print additional section
[ad]
[no] dnssec (dn) set the DNSSEC OK bit in
the OPT
pseudo record [nodn]
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 retrans-
mission strategy
used by the resolver library when sending data-
gram 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) li-
brary. As of BIND 4.9, BIND's resolver has been augmented
to work prop-
erly with dig. Essentially, dig is a straight-forward (al-
beit not pretty)
effort of parsing arguments and setting appropriate parame-
ters. Dig uses
resolver(3) routines res_init(), res_mkquery(), res_send()
as well as ac-
cessing 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 op-
tions, above.
FILES
/etc/resolv.conf initial domain name and name server ad-
dresses
./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 sta-
tus) when a
problem occurs somewhere in the resolver (NOTE: most of the
common exit
cases are handled). This is particularly annoying when run-
ning in batch
mode. If it exits abnormally (and is not caught), the en-
tire batch
aborts; when such an event is trapped, dig simply continues
with the next
query.
4th Berkeley Distribution August 30, 1990
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