nslookup.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH nslookup 1
.SH Name
nslookup \- interactively query servers running BIND, or BIND and
Hesiod together
.SH Syntax
.NXR "nslookup command"
.B /usr/ucb/nslookup
[
.I host
][
.I server
]
.br
.B /usr/ucb/nslookup
[
.B \-
][
.I server
]
.SH Description
The
.PN nslookup
command queries the BIND/Hesiod servers. 
This command has two modes: interactive and non-interactive.
Interactive mode allows you to query the BIND/Hesiod server for
information about various hosts and domains.
Non-interactive mode allows you to 
obtain just the name and Internet address of a host or domain.
.PP
Use interactive mode if you have no arguments to provide.
In this case,
.PN nslookup
queries the default BIND/Hesiod server.
To specify a BIND/Hesiod server to query,
the first argument should be a dash (\fB\-\fR)
and the second argument should be the name of the server.
.PP
Use non-interactive mode when the name of the host you
are looking up is the first argument.
The optional second argument specifies a BIND/Hesiod server.
If you do not supply a second argument,
the current BIND/Hesiod server is queried.
.PP
To terminate the
.PN nslookup
command from within interactive mode,
press <CTRL/D>.
To terminate only the current lookup activity,
press <CTRL/C>.
.SH Non-interactive Options
.IP "\fIhost \fR[\fIserver\fR]" 5
The \fIhost\fR option is the name of the host for 
which you are looking up information.
If you do not specify a 
.I server,
the default server is queried.
You can specify the 
.I server 
by either name or IP address.
.IP "\fB\-\fR  [\fIserver\fR]"
The
.B \-
option returns the name and IP address of the default server,
or the 
.I server 
you specify.
It then places you in interactive mode.
If you do not specify a 
.I server,
the default server is queried.
You can specify the 
.I server 
by either name or IP address.
.SH Interactive Options
The command line length must be less than 80 characters.
Any unrecognized command is interpreted as a host name.
The following are the standard options:
.IP "\fIhost\fR [\fIserver\fR]" 5
Looks up information for \fIhost\fP using the current default server
or using \fIserver\fP if it is specified.
.IP "\fBserver\fP \fIserver\fP"
Changes the default server to the 
.I server 
specified.
This option uses the current default server. 
.IP "\fBlserver\fP \fIserver\fP"
Changes the default server to the 
.I server 
specified.
This option uses the initial default server to look up 
information about the server specified.
.IP \fBroot\fR
Changes the default server to the server for the root of the
domain name space specified.
Currently, the host ns.nic.ddn.mil is used.
.IP "\fBfinger\fP [ \fIname\fP ] [ \fB>\fP [ \fB>\fP ] \fIfile\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=\fIvalue\fR command.
The
.I name
field is optional; but if used, it specifies a user name.
You can use the
\fB>\fP
and
\fB>>\fP
options to redirect output to the file specified.
.IP "\fBls\fR [ \fB\-adhlmst\fR ] \fIdomain\fP [ \fB>\fR [ \fB>\fR ] \fIfile\fP ]"
Lists the information available for the 
.I domain 
specified.
The default output contains host names and their Internet addresses. 
.RS
.IP \-a 10
Lists aliases of hosts in the 
.I domain, 
CNAME entries.
.IP  \-d
Lists all entries in the 
.I domain.
.IP \-h
Lists CPU and operating system information for the 
.I domain, 
HINFO entries.
.IP \-l
Same as \-d.
.IP \-m
Lists mail exchangers in the 
.I domain, 
MX entries.
.IP \-s
Lists well known services in the 
.I domain, 
WKS entries.
.IP \-t
Lists Hesiod text information, TXT entries.
.RE
.IP " " 5
If you redirect the output to a file,
hash marks are printed for every
50 records received from the server.
.RE
.IP "\fBview\fP \fIfile\fP" 5
Sorts and lists the output of the
.PN ls
command with the
.PN more
command.
.IP "help \fRor\fP ?"
Print a brief summary of the
.PN nslookup 
commands and options.
.IP "\fBset\fR \fIkeyword\fP[=\fIvalue\fP]"
Changes the set options that affect the lookups,
except for keywords 
.PN all
and 
.PN ALL 
which display information.
Valid keywords are:
.RS
.IP "\fBall\fP" 10
Prints the current values of the options you can set,
as well as information about the current default server.
.IP "\fBALL\fP"
Prints the current values of the options you can set,
as well as information about the current default server.
In addition,
the
.B ALL
option prints the server state information.
.IP "\fB[no]debug\fP"
Turns on debugging mode.
Verbose information is printed about the
packet sent to the server and the resulting answer.
.IP
The default is
.B nodebug ,
which you can abbreviate to [\fBno]\fBdeb\fR.
.IP "\fB[no]defname\fP"
Appends the default domain name to every lookup.
The default is
.B nodefname,
which you can abbreviate to [\fBno\fR]\fBdef\fR.
.IP "\fB[no]recurse\fP"
Tells the BIND/Hesiod server to query other servers if it does not have the
information.
The default is
.B recurse,
and the abbreviation is [\fBno\fR]\fBrec\fR.
.IP "\fB[no]vc\fP"
Uses a TCP connection when sending requests to the server.
The default is
.B novc,
and the abbreviation is
[\fBno\fR]\fBv\fR.
.IP "\fBdomain=\fIname\fR"
Changes the default domain to the domain 
.I name 
specified.
The default domain name is appended to all lookup requests if 
the \fBdefname\fP option is set.
The default value is set in the
.PN /etc/resolv.conf
file, which you can abbreviate to
.B do.
.IP "\fBclass=\fIvalue\fR"
Changes the class of information returned from a query
to one of the following values:
.RS
.IP IN 10
Internet (default)
.IP HS 10
Hesiod 
.IP ANY 10
any
.RE
.IP
The abbreviation for the
.B class
option is
.B cl.
.IP "\fBquerytype=\fIvalue\fR"
Changes the type of information returned from a query to 
.I value.
The following is a list of the most common 
values:
.RS
.IP A 10
host Internet address (default)
.IP CNAME 10
canonical name for an alias
.IP MX 10
mail exchanger
.IP NS 10
name server
.IP PTR 10
host Internet name
.IP SOA 10
Start of authority
.IP TXT 10
A Hesiod data query
.IP WKS 10
A well known service
.RE
.IP
The abbreviation for the
.B querytype
option is
.B q.
.IP \fBretry=\fInumber\fR
Sets the number of retries to the 
.I number 
specified.
If a reply to a request is not received within a certain 
amount of time (changed with \fBset timeout\fP), 
the request is resent. 
The retry value controls how many times a request
is to be resent before giving up.
The default retry number is
.PN 2 ,
and the abbreviation for the
.B retry
option is
.B ret.
.IP \fBroot=\fIhost\fR
Changes the name of the root server to the 
.I host 
name specified.
This affects the \fBroot\fP command. 
The default is
.PN .ns.nic.ddn.mil ,
and the abbreviation is
.B ro.
.IP \fBtimeout=\fInumber\fR
Changes the time-out interval for waiting for a reply to the
.I number 
specified (in seconds).
The default is 10 seconds, and the abbreviation for the
.B timeout
option is
.B  t.
.RE
.SH Tutorial
The domain name space is tree-structured and has six top-level
domains: 
.IP \(bu 5
ARPA (for ARPAnet hosts)
.sp 6p
The ARPA domain is currently one of the top-level domains,
but is being phased out.
.IP \(bu 5
COM (for commercial establishments)
.IP \(bu
EDU (for educational institutions)
.IP \(bu
GOV (for government agencies)
.IP \(bu
ORG (for not for profit organizations)
.IP \(bu
MIL (for MILNET hosts)
.PP
If you are looking for a specific host, 
you need to know something about the host's organization  
in order to determine the top-level domain it belongs to.
For instance,
if you want to find the Internet address of a host at UCLA,
do the following:
.IP 1. 5
Connect with the root server,
using the
.PN root
command.
The root server of the name space has knowledge of the top-level
domains.
.IP 2. 5
Connect with a server for the
.PN ucla.edu
domain.
The domain name for UCLA,
which is a university, is
.PN ucla.edu .
To connect with this server,
you can type:
.EX
# nslookup
>  server ucla.edu
.EE
The response is
the names of the hosts that act as servers for the domain
.PN ucla.edu .
Note that the root server does not have information about
.PN ucla.edu ,
but knows the names and addresses of hosts that do.
All future queries are sent to the UCLA BIND server.
.IP 3. 5
Request information about a particular host in the domain,
for example,
.PN purple .
To do this,
type the host name. 
To request a list of hosts in the UCLA domain,
use the
.PN ls
command.
The
.PN ls
command requires a domain name (in this case,
.PN ucla.edu )
as an argument.
.PP
Note that if you are connected with a BIND server that handles
more than one domain,
all lookups for host names must be fully specified with its domain.
For instance, the domain
.PN harvard.edu
is served by
.PN seismo.css.gov ,
which also services the
.PN css.gov
and
.PN cornell.edu
domains.
A lookup request for the host
.PN novel
in the
.PN harvard.edu
domain must be specified as
.PN novel.harvard.edu. 
However,
you can use the \fBset domain=\fIname\fR and \fBset defname\fP
commands to automatically append a domain name to each request.
.PP
After a successful lookup of a host,
use the
.PN finger
command to see who is on the system or to get information
about  a specific person.
To get other information about the host,
use the \fBset querytype=\fIvalue\fR command,
which allows you to change the type of information obtained
and request another lookup. 
The
.PN finger
command requires that the information requested information be
of type A, a host Internet address.
.SH Hesiod Tutorial
If you  have set up Hesiod on your ULTRIX system and would
like to look at this information, you must use the 
.PN "set class=\fIvalue"\fR
and 
.PN "set querytype=\fIvalue"\fR
commands, where value is HS and TXT respectively.
.PP
The following example presumes that the
.PN networks
database is set up to be distributed with BIND/Hesiod.  The
answer received from the
.PN nslookup
command is that 128.45 is the network number for the 
network named
.PN ethernet
in the networks.dec.com domain.
.EX
# \f(CBnslookup\f(CW
Default Server:  localhost.dec.com
Address:  127.0.0.1

> \f(CBset cl=hs\f(CW
> \f(CBset q=txt\f(CW
> \f(CBethernet.networks\f(CW
Server:  localhost.dec.com
Address:  127.0.0.1

ethernet.networks.dec.com  ethernet:128.45
>
.EE
.SH Diagnostics
If the lookup request was not successful, the
.PN nslookup
command displays one of the following error messages:
.IP "Time-out" 0
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 information"
Depending on the query type set with the \fBset querytype\fP command,
no information about the host was available,
although the host name is valid.
.IP "Non-existent domain"
The host or domain name does not exist.
.IP "Connection refused"
The connection to the BIND/Hesiod server was refused.
.IP "Network is unreachable"
The connection to the BIND/Hesiod server cannot be made 
at the current time.
.IP "Server failure"
The BIND/Hesiod server found an internal inconsistency in its database
and could not return a valid answer.
.IP "Refused"
The BIND/Hesiod server refused to service the request.
.IP "Format error"
The name server found that the request packet was not in the proper
format.
Contact your DIGITAL Field Service representative.
.SH Files
.TP 20
.PN /var/dss/namedb
BIND server data file directory
.TP 20
.PN /var/dss/namedb/named.boot	
BIND server boot file
.TP 20
.PN /var/dss/namedb/hosts.db
BIND primary server hosts file
.TP 20
.PN /var/dss/namedb/hosts.rev
BIND primary server reverse address hosts file
.TP 20
.PN /var/dss/namedb/named.local	
BIND server local host reverse address host file
.TP 20
.PN /var/dss/namedb/named.ca	
BIND server cache file
.TP 20
.PN /etc/resolv.conf	
BIND data file
.SH See Also
finger(1), more(1), nsquery(1), resolver(3), resolver(5), named(8)
.br
\fIGuide to the BIND/Hesiod Service\fP