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.\"	@(#)nslookup.8	5.3 (Berkeley) 6/24/90
.\"
.TH NSLOOKUP 8 "June 24, 1990"
.UC 6
.SH NAME
nslookup \- query Internet name servers interactively
.SH SYNOPSIS
.B nslookup
[ 
.I \-option ...
]
[
.I host-to-find
| \- [
.I server
]] 
.SH DESCRIPTION
.I 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-interactive mode is used to print just the name and requested information
for a host or domain.
.sp 1
.SH ARGUMENTS
Interactive mode is entered in the following cases:
.IP a) 4
when no arguments are given (the default name server will be used),
.IP b) 4
when the first argument is a hyphen (\-) and the second argument
is the host name or Internet address of a name server.
.LP
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.
.LP
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:
.sp .5v
	nslookup \-query=hinfo  \-timeout=10
.sp .5v
.SH "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 (\e). 
\fBN.B.\fP an unrecognized command will be interpreted as a host name.
.sp .5v
.IP "\fIhost\fP [\fIserver\fP]"
Look up information for \fIhost\fP using the current default server
or using \fIserver\fP if specified.
If \fIhost\fP is an Internet address and the query type is A or PTR, the 
name of the host is returned.
If \fIhost\fP 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
\fBset\fP options \fBdomain\fP, \fBsrchlist\fP, 
\fBdefname\fP, and \fBsearch\fP).
To look up a host not in the current domain, append a period to 
the name.
.sp 1
.IP "\fBserver\fP \fIdomain\fP"
.ns
.IP "\fBlserver\fP \fIdomain\fP"
Change the default server to \fIdomain\fP. 
\fBLserver\fP uses the initial server to look up 
information about \fIdomain\fP while \fBserver\fP
uses the current default server. 
If an authoritative answer can't be found, the names of servers
that might have the answer are returned.
.sp 1
.IP \fBroot\fP
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 \fBlserver ns.internic.net.\fP)
The name of the root server can be changed with the \fBset root\fP command.
.sp 1
.IP "\fBfinger\fP [\fIname\fP] [\fB>\fP \fIfilename\fP]"
.ns
.IP "\fBfinger\fP [\fIname\fP] [\fB>>\fP \fIfilename\fP]"
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 
\fBset querytype=A\fP command).
\fIName\fP is optional. 
\fB>\fP and \fB>>\fP can be used to redirect output in the
usual manner.
.sp 1
.IP "\fBls\fR [\fIoption\fR] \fIdomain\fR [\fB>\fR \fIfilename\fR]"
.ns
.IP "\fBls\fR [\fIoption\fR] \fIdomain\fR [\fB>>\fR \fIfilename\fR]"
List the information available for \fIdomain\fP, optionally creating
or appending to \fIfilename\fP.
The default output contains host names and their Internet addresses. 
.I Option 
can be one of the following:
.RS
.IP "\fB\-t \fIquerytype\fP" 4
lists all records of the specified type (see \fIquerytype\fP below).
.IP \fB\-a\fP 4
lists aliases of hosts in the domain. 
synonym for \fB\-t\ \ CNAME\fP.
.IP \fB\-d\fP 4
lists all records for the domain.
synonym for \fB\-t\ \ ANY\fP.
.IP \fB\-h\fP 4
lists CPU and operating system information for the domain.
synonym for \fB\-t\ \ HINFO\fP.
.IP \fB\-s\fP 4
lists well-known services of hosts in the domain.
synonym for \fB\-t\ \ WKS\fP.
.P
When output is directed to a file, hash marks are printed for every
50 records received from the server.
.RE
.sp 1
.IP "\fBview\fP \fIfilename\fP"
Sorts and lists the output of previous \fBls\fP command(s) with \fImore\fP(1).
.sp 1
.ne 4
.IP "\fBhelp\fP"
.ns
.IP "\fB?\fP"
Prints a brief summary of commands.
.sp 1
.IP "\fBexit\fP"
Exits the program.
.sp 1
.IP "\fBset\fP \fIkeyword\fP[=\fIvalue\fP]"
This command is used to change state information that affects the lookups.
Valid keywords are:
.RS
.IP "\fBall\fP"
Prints the current values of the frequently-used options to \fBset\fP.
Information about the  current default server and host is also printed.
.IP "\fBclass=\fIvalue\fR"
Change the query class to one of:
.RS
.IP IN 10
the Internet class.
.IP CHAOS 10
the Chaos class.
.IP HESIOD 10
the MIT Athena Hesiod class.
.IP ANY 10
wildcard (any of the above).
.P
The class specifies the protocol group of the information.
.br
(Default = IN, abbreviation = cl)
.RE
.IP "\fB[no]debug\fP"
Turn debugging mode on. A lot more information is printed about the
packet sent to the server and the resulting answer.
.br
(Default = nodebug, abbreviation = [no]deb)
.IP "\fB[no]d2\fP"
Turn exhaustive debugging mode on.
Essentially all fields of every packet are printed.
.br
(Default = nod2)
.IP "\fBdomain=\fIname\fR"
Change the default domain name to \fIname\fP. 
The default domain name is appended to a lookup request depending on the
state of the \fBdefname\fP and \fBsearch\fP 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 \fBset srchlist\fP command to specify a different list.
Use the \fBset all\fP command to display the list.
.br
(Default = value from hostname, /etc/resolv.conf or LOCALDOMAIN, 
abbreviation = do)
.IP "\fBsrchlist=\fIname1/name2/...\fR"
Change the default domain name to \fIname1\fP and the domain search list
to \fIname1\fP, \fIname2\fP, etc. A maximum of 6 names separated by slashes (/)
can be specified.
For example,
.sp .5v
    set\ srchlist=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU
.sp .5v
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 \fBset domain\fP command.
Use the \fBset all\fP command to display the list.
.br
(Default = value based on hostname, /etc/resolv.conf or LOCALDOMAIN, 
abbreviation = srchl)
.IP "\fB[no]defname\fP"
If set, append the default domain name to a single-component lookup request 
(i.e., one that does not contain a period).
.br
(Default = defname, abbreviation = [no]def)
.IP "\fB[no]search\fP"
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.
.br
(Default = search, abbreviation = [no]sea)
.IP "\fBport=\fIvalue\fR"
Change the default TCP/UDP name server port to \fIvalue\fP. 
.br
(Default = 53, abbreviation = po)
.IP "\fBquerytype=\fIvalue\fR"
.ns
.IP "\fBtype=\fIvalue\fR"
.ns
Change the type of information query to one of:
.RS
.IP A 10
the host's Internet address.
.IP CNAME  10
the canonical name for an alias. 
.IP HINFO 10
the host CPU and operating system type.
.IP MINFO 10
the mailbox or mail list information.
.IP MX 10
the mail exchanger.
.IP NS 10
the name server for the named zone.
.IP PTR 10
the host name if the query is an Internet address,
otherwise the pointer to other information.
.IP SOA 10
the domain's ``start-of-authority'' information.
.IP TXT 10
the text information.
.IP UINFO 10
the user information.
.IP WKS 10
the supported well-known services.
.P
Other types (ANY, AXFR, MB, MD, MF, NULL) are described in the 
RFC-1035 document.
.br
(Default = A, abbreviations = q, ty)
.RE
.IP "\fB[no]recurse\fP"
Tell the name server to query other servers if it does not have the
information.
.br
(Default = recurse, abbreviation = [no]rec)
.IP \fBretry=\fInumber\fR
Set the number of retries to \fInumber\fP. 
When a reply to a request is not received within a certain 
amount of time (changed with \fBset timeout\fP), 
the timeout period is doubled and the request is resent. 
The retry value controls how many times a request is resent before giving up.
.br
(Default = 4, abbreviation = ret)
.IP \fBroot=\fIhost\fR
Change the name of the root server to \fIhost\fP. This
affects the \fBroot\fP command. 
.br
(Default = ns.internic.net., abbreviation = ro)
.IP \fBtimeout=\fInumber\fR
Change the initial timeout interval 
for waiting for a reply 
to \fInumber\fP seconds. 
Each retry doubles the timeout period.
.br
(Default = 5 seconds, abbreviation = ti)
.IP "\fB[no]vc\fP"
Always use a virtual circuit when sending requests to the server.
.br
(Default = novc, abbreviation = [no]v)
.IP "\fB[no]ignoretc\fP"
Ignore packet truncation errors.
.br
(Default = noignoretc, abbreviation = [no]ig)
.RE
.SH DIAGNOSTICS
If the lookup request was not successful, an error message is printed.
Possible errors are:
.IP "Timed out" 5
The server did not respond to a request after a certain amount of
time (changed with \fBset timeout=\fIvalue\fR) 
and a certain number of retries (changed with \fBset retry=\fIvalue\fR).
.IP "No response from server" 5
No name server is running on the server machine.
.IP "No records" 5
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 \fBset querytype\fP command.
.IP "Non-existent domain" 5
The host or domain name does not exist.
.IP "Connection refused" 5
.ns
.IP "Network is unreachable" 5
The connection to the name or finger server could not be made 
at the current time.
This error commonly occurs with \fBls\fP and \fBfinger\fP requests. 
.IP "Server failure" 5
The name server found an internal inconsistency in its database
and could not return a valid answer.
.IP "Refused" 5
The name server refused to service the request.
.IP "Format error" 5
The name server found that the request packet was not in the proper format.
It may indicate an error in \fInslookup\fP.
.sp 1
.SH FILES
.ta \w'/usr/share/misc/nslookup.helpXXX'u
/etc/resolv.conf	initial domain name and 
	name server addresses.
.br
$HOME/.nslookuprc	user's initial options.
.br
/usr/share/misc/nslookup.help	summary of commands.
.SH ENVIRONMENT
.ta \w'HOSTALIASESXXXX'u
HOSTALIASES	file containing host aliases.
.br
LOCALDOMAIN	overrides default domain.
.SH SEE ALSO
resolver(3), resolver(5), named(8), 
.br
RFC-1034  ``Domain Names \- Concepts and Facilities''
.br
RFC-1035  ``Domain Names \- Implementation and Specification''
.SH AUTHOR
Andrew Cherenson