NSLOOKUP(8) RISC/os Reference 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-interactive mode is used to
print just the name and requested information for 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),
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 direc-
tory 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
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. 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 specified. If host is an
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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.nic.ddn.mil is used. (This command is a synonym for
lserver ns.nic.ddn.mil.) 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:
-t querytype
lists all records of the specified type (see
querytype below).
-a lists aliases of hosts in the domain. synonym for
-t CNAME.
-d lists all records for the domain. synonym for
-t ANY.
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-h lists CPU and operating system information for the
domain. synonym for -t HINFO.
-s lists well-known services of hosts in the domain.
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 command(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 frequently-used
options to set. Information about the current
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
information.
(Default = IN, abbreviation = cl)
[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)
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[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 speci-
fied. 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)
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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 system type.
MINFO the mailbox or mail list information.
MX the mail exchanger.
NS the name server for the named zone.
PTR the host name if the query is an Inter-
net address, otherwise the pointer to
other information.
SOA the domain's ``start-of-authority''
information.
TXT the text information.
UINFO the user information.
WKS the supported well-known services.
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
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.nic.ddn.mil., abbreviation = ro)
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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)
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 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
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in the proper format. It may indicate an error in
nslookup.
FILES
/etc/resolv.conf initial domain name and
name server addresses.
$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
resolver(3), resolver(5), named(8),
RFC-1034 ``Domain Names - Concepts and Facilities''
RFC-1035 ``Domain Names - Implementation and Specifica-
tion''
AUTHOR
Andrew Cherenson
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