NSLOOKUP(8) BSD System Manager's Manual
NSLOOKUP(8)
NAME
nslookup - query Internet name servers interactively
SYNOPSIS
nslookup [-option ...] [host-to-find | -[server]]
DESCRIPTION
Nslookup is a program to query Internet domain name servers.
Nslookup
has two modes: interactive and non-interactive. Interactive
mode allows
the user to query name servers for information about various
hosts and
domains or to print a list of hosts in a domain. Non-inter-
active mode is
used to print just the name and requested information for a
host or do-
main.
ARGUMENTS
Interactive mode is entered in the following cases:
a) when no arguments are given (the default name server
will be used),
b) when the first argument is a hyphen (-) and the second
argument is
the host name or Internet address of a name server.
Non-interactive mode is used when the name or Internet ad-
dress of the
host to be looked up is given as the first argument. The op-
tional second
argument specifies the host name or address of a name serv-
er.
The options listed under the ``set'' command below can be
specified in
the .nslookuprc file in the user's home directory if they
are listed one
per line. Options can also be specified on the command line
if they pre-
cede the arguments and are prefixed with a hyphen. For ex-
ample, to
change the default query type to host information, and the
initial time-
out to 10 seconds, type:
nslookup -query=hinfo -timeout=10
INTERACTIVE COMMANDS
Commands may be interrupted at any time by typing a control-
C. To exit,
type a control-D (EOF) or type exit. The command line length
must be less
than 256 characters. To treat a built-in command as a host
name, precede
it with an escape character (.& .) N.B.: unrecognized com-
mand will be
interpreted as a N.B.:0 0N.B.:1
host [server]
Look up information for host using the current de-
fault server or
using server, if specified. If host is an Internet
address and
the query type is A or PTR, the name of the host is
returned.
If host is a name and does not have a trailing pe-
riod, the de-
fault domain name is appended to the name. (This
behavior de-
pends on the state of the set options domain,
srchlist, defname,
and search.)
To look up a host not in the current domain, append
a period to
the name.
server domain
lserver domain
Change the default server to domain; lserver uses
the initial
server to look up information about domain, while
server uses
the current default server. If an authoritative
answer can't be
found, the names of servers that might have the an-
swer are re-
turned.
root Changes the default server to the server for the
root of the do-
main name space. Currently, the host ns.inter-
nic.net is used.
(This command is a synonym for ``lserver
ns.internic.net''.) The
name of the root server can be changed with the
``set root''
command.
finger [name] [> filename]
finger [name] [>> filename]
Connects with the finger server on the current
host. The cur-
rent host is defined when a previous lookup for a
host was suc-
cessful and returned address information (see the
``set
querytype=A'' command). The name is optional. >
and >> can be
used to redirect output in the usual manner.
ls [option] domain [> filename]
ls [option] domain [>> filename]
List the information available for domain, option-
ally creating
or appending to filename. The default output con-
tains host names
and their Internet addresses. Option can be one of
the follow-
ing:
-t querytype
lists all records of the specified type (see
querytype be-
low).
-a lists aliases of hosts in the domain; synonym
for ``-t
CNAME''.
-d lists all records for the domain; synonym for
``-t ANY''.
-h lists CPU and operating system information
for the domain;
synonym for ``-t HINFO''.
-s lists well-known services of hosts in the do-
main; synonym
for ``-t WKS''.
When output is directed to a file, hash marks are
printed for
every 50 records received from the server.
view filename
Sorts and lists the output of previous ls com-
mand(s) with
more(1).
help
? Prints a brief summary of commands.
exit Exits the program.
set keyword[=value]
This command is used to change state information
that affects
the lookups. Valid keywords are:
all Prints the current values of the frequent-
ly-used op-
tions to set. Information about the cur-
rent default
server and host is also printed.
class=value
Change the query class to one of:
IN the Internet class
CHAOS the Chaos class
HESIOD the MIT Athena Hesiod class
ANY wildcard (any of the above)
The class specifies the protocol group of
the informa-
tion.
(Default = IN; abbreviation = cl)
[no]debug
Turn debugging mode on. A lot more infor-
mation is
printed about the packet sent to the serv-
er and the re-
sulting answer.
(Default = nodebug; abbreviation =
[no]deb)
[no]d2 Turn exhaustive debugging mode on. Essen-
tially all
fields of every packet are printed.
(Default = nod2)
domain=name
Change the default domain name to name.
The default do-
main name is appended to a lookup request
depending on
the state of the defname and search op-
tions. The do-
main search list contains the parents of
the default
domain if it has at least two components
in its name.
For example, if the default domain is
CC.Berkeley.EDU,
the search list is CC.Berkeley.EDU and
Berkeley.EDU.
Use the ``set srchlist'' command to speci-
fy a different
list. Use the ``set all'' command to dis-
play the list.
(Default = value from hostname(1),
/etc/resolv.conf,
or LOCALDOMAIN; abbreviation = do)
srchlist=name1/name2/...
Change the default domain name to name1
and the domain
search list to name1, name2, etc. A maxi-
mum of 6 names
separated by slashes (/) can be specified.
For exam-
ple,
set srch-
list=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU
sets the domain to lcs.MIT.EDU and the
search list to
the three names. This command overrides
the default
domain name and search list of the ``set
domain'' com-
mand. Use the ``set all'' command to dis-
play the list.
(Default = value based on hostname(1),
/etc/resolv.conf, or LOCALDOMAIN; abbrevi-
ation = srchl)
[no]defname
If set, append the default domain name to
a single-com-
ponent lookup request (i.e., one that does
not contain
a period).
(Default = defname; abbreviation =
[no]defname)
[no]search
If the lookup request contains at least
one period but
doesn't end with a trailing period, append
the domain
names in the domain search list to the re-
quest until an
answer is received.
(Default = search; abbreviation = [no]sea)
port=value
Change the default TCP/UDP name server
port to value.
(Default = 53; abbreviation = po)
querytype=value
type=value
Change the type of information query to
one of:
A the host's Internet address.
CNAME the canonical name for an alias.
HINFO the host CPU and operating sys-
tem type.
MINFO the mailbox or mail list infor-
mation.
MX the mail exchanger.
NS the name server for the named
zone.
PTR the host name if the query is an
Internet ad-
dress; otherwise, the pointer to
other infor-
mation.
SOA the domain's ``start-of-authori-
ty'' informa-
tion.
TXT the text information.
UINFO the user information.
WKS the supported well-known ser-
vices.
Other types (ANY, AXFR, MB, MD, MF, NULL)
are described
in the RFC-1035 document.
(Default = A; abbreviations = q, ty)
[no]recurse
Tell the name server to query other
servers if it does
not have the information.
(Default = recurse; abbreviation =
[no]rec)
retry=number
Set the number of retries to number. When
a reply to a
request is not received within a certain
amount of time
(changed with ``set timeout''), the time-
out period is
doubled and the request is resent. The
retry value
controls how many times a request is re-
sent before giv-
ing up.
(Default = 4, abbreviation = ret)
root=host
Change the name of the root server to
host. This af-
fects the ``root'' command.
(Default = ns.internic.net.; abbreviation
= ro)
timeout=number
Change the initial timeout interval for
waiting for a
reply to number seconds. Each retry dou-
bles the timeout
period.
(Default = 5 seconds; abbreviation = ti)
[no]vc Always use a virtual circuit when sending
requests to
the server.
(Default = novc; abbreviation = [no]v)
[no]ignoretc
Ignore packet truncation errors.
(Default = noignoretc; abbreviation =
[no]ig)
DIAGNOSTICS
If the lookup request was not successful, an error message
is printed.
Possible errors are:
Timed out
The server did not respond to a request after a cer-
tain amount of
time (changed with ``set timeout=value'') and a cer-
tain number of
retries (changed with ``set retry=value'').
No response from server
No name server is running on the server machine.
No records
The server does not have resource records of the cur-
rent query
type for the host, although the host name is valid.
The query
type is specified with the ``set querytype'' command.
Non-existent domain
The host or domain name does not exist.
Connection refused
Network is unreachable
The connection to the name or finger server could not
be made at
the current time. This error commonly occurs with ls
and finger
requests.
Server failure
The name server found an internal inconsistency in
its database
and could not return a valid answer.
Refused
The name server refused to service the request.
Format error
The name server found that the request packet was not
in the prop-
er format. It may indicate an error in nslookup.
FILES
/etc/resolv.conf initial domain name and
name server ad-
dresses
$HOME/.nslookuprc user's initial options
/usr/share/misc/nslookup.help summary of commands
ENVIRONMENT
HOSTALIASES file containing host aliases
LOCALDOMAIN overrides default domain
SEE ALSO
named(8), resolver(3), resolver(5); RFC-1034, ``Domain
Names -
Concepts and Facilities''; RFC-1035, ``Domain Names - Imple-
mentation and
Specification''.
AUTHOR
Andrew Cherenson
4th Berkeley Distribution June 24, 1990
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