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 address of the host to be looked up is given as the first argument. The optional second argument specifies the host name or address of a name server.
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 precede the
arguments and are prefixed with a hyphen. For example, to
change the default query type to host information, and the
initial timeout to 10 seconds, type:
nslookup -query=hinfo -timeout=10
host [server]
Look up information for host using the current
default 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 period, the
default domain name is appended to the name. (This
behavior depends 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 answer are
returned.
root Changes the default server to the server for the root of the domain name space. Currently, the host ns.internic.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 current host is defined when a previous
lookup for a host was successful and returned
address information (see the set querytype=A command).
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, optionally
creating or appending to filename. The
default output contains host names and their Internet
addresses. Option can be one of the following:
view filename
Sorts and lists the output of previous ls command(s)
with more(1).
help
[no]debug
Turn debugging mode on. A lot more information
is printed about the packet sent to the
server and the resulting answer.
(Default = nodebug, abbreviation = [no]deb)
[no]d2 Turn exhaustive debugging mode on. Essentially all fields of every packet are printed. (Default = nod2)
domain=name
Change the default domain name to name. The
default domain name is appended to a lookup
request depending on the state of the defname
and search options. The domain 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 specify a different
list. Use the set all command to
display the list.
(Default = value from hostname,
/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 maximum of 6 names separated by slashes
(/) can be specified. For example,
set srchlist=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 command. Use
the set all command to display the list.
(Default = value based on hostname,
/etc/resolv.conf or LOCALDOMAIN, abbreviation
= srchl)
[no]defname
If set, append the default domain name to a
single-component lookup request (i.e., one
that does not contain a period).
(Default = defname, abbreviation = [no]def)
[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 request 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:
[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 timeout period is doubled and
the request is resent. The retry value controls
how many times a request is resent
before giving up.
(Default = 4, abbreviation = ret)
root=host
Change the name of the root server to host.
This affects 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 doubles 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)
Timed out
The server did not respond to a request after a certain
amount of time (changed with set timeout=value)
and a certain 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 current
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 proper format. It may indicate an error in
nslookup.