NSLOOKUP(1N) UNIX 5.0 (November 21, 1987) NSLOOKUP(1N)
NAME
nslookup - query name servers interactively
SYNOPSIS
nslookup [ host-to-find | - [ server address | server name
]]
DESCRIPTION
Nslookup is a program to query DARPA Internet domain name
servers. Nslookup has two modes: interactive and non-
interactive. Interactive mode allows the user to query the
name server for information about various hosts and domains
or print a list of hosts in the domain. Non-interactive mode
is used to print just the name and Internet address of a
host or domain.
ARGUMENTS
Interactive mode is entered in the following cases:
a) when no arguments are given (the default name server
will be used), and
b) when the first argument is a hyphen (-) and the second
argument is the host name of a name server.
Non-interactive mode is used when the name of the host to be
looked up is given as the first argument. The optional
second argument specifies a name server.
INTERACTIVE COMMANDS
Commands may be interrupted at any time by typing a
control-C. To exit, type a control-D (EOF). The command
line length must be less than 80 characters. N.B. an
unrecognized command will be interpreted as a host name.
host [server]
Look up information for host using the current default
server or using server if it is specified.
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.
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root Changes the default server to the server for the root
of the domain name space. Currently, the host sri-
nic.arpa is used. (This command is a synonym for the
lserver sri-nic.arpa.) 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 domain [> filename]
ls domain [>> filename]
ls -a domain [> filename]
ls -a domain [>> filename]
ls -h domain [> filename]
ls -h domain [>> filename]
ls -d domain [> filename]
List the information available for domain. The default
output contains host names and their Internet
addresses. The -a option lists aliases of hosts in the
domain. The -h option lists CPU and operating system
information for the domain. The -d option lists all
contents of a zone transfer. 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 command(s)
with more(1).
help
? Prints a brief summary of commands.
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 various options
to set. Information about the current default
server and host is also printed.
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NSLOOKUP(1N) UNIX 5.0 (November 21, 1987) NSLOOKUP(1N)
[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)
[no]defname
Append the default domain name to every lookup.
(Default = defname, abbreviation = [no]def)
[no]search
With defname, search for each name in parent
domains of the current domain.
(Default = search)
domain=name
Change the default domain name to name. The
default domain name is appended to all lookup
requests if the defname option has been set. The
search list is set to parents of the domain with
at least two components in their names.
(Default = value in hostname or /etc/resolv.conf,
abbreviation = do)
querytype=value
type=value
Change the type of information returned from a
query to one of:
A the host's Internet address (the
default).
CNAME the canonical name for an alias.
HINFO the host CPU and operating system type.
MD the mail destination.
MX the mail exchanger.
MG the mail group member.
MINFO the mailbox or mail list information.
MR the mail rename domain name.
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NSLOOKUP(1N) UNIX 5.0 (November 21, 1987) NSLOOKUP(1N)
NS nameserver for the named zone.
Other types specified in the RFC883 document are valid
but aren't very useful.
(Abbreviation = q)
[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
request is resent. The retry value controls how
many times a request is resent before giving up.
(Default = 2, abbreviation = ret)
root=host
Change the name of the root server to host. This
affects the root command.
(Default = sri-nic.arpa, abbreviation = ro)
timeout=number
Change the time-out interval for waiting for a
reply to number seconds.
(Default = 10 seconds, abbreviation = t)
[no]vc
Always use a virtual circuit when sending requests
to the server.
(Default = novc, abbreviation = [no]v)
DIAGNOSTICS
If the lookup request was not successful, an error message
is printed. Possible errors are:
Time-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 information
Depending on the query type set with the set querytype
command, no information about the host was available,
though the host name is valid.
Non-existent domain
The host or domain name does not exist.
Connection refused
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Network is unreachable
The connection to the name or finger server could not
be made at the current time. This error commonly
occurs with 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.
The following error should not occur and it indicates a bug
in the program.
Format error
The name server found that the request packet was not
in the proper format.
FILES
/etc/resolv.conf initial domain name and name server
addresses.
SEE ALSO
resolver(3N), resolver(4) RFC882, RFC883
AUTHOR
Andrew Cherenson
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