NSLOOKUP(1) BIND 9 NSLOOKUP(1)

NAME

nslookup - query Internet name servers interactively

SYNOPSIS

nslookup [-option] [name | -] [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 prints 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 is 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.

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, with an initial timeout of 10
seconds, type:

nslookup -query=hinfo -timeout=10

The -version option causes nslookup to print the version number and
immediately exit.

INTERACTIVE COMMANDS

host [server]
This command looks 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 search list is used to qualify the
name.

To look up a host not in the current domain, append a period
to the name.

server domain | lserver domain
These commands 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 cannot be found, the names of servers
that might have the answer are returned.

root This command is not implemented.

finger This command is not implemented.

ls This command is not implemented.

view This command is not implemented.

help This command is not implemented.

? This command is not implemented.

exit This command exits the program.

set keyword[=value]
This command is used to change state information that affects
the lookups. Valid keywords are:

all This keyword prints the current values of the
frequently used options to set. Information about the
current default server and host is also printed.

class=value
This keyword changes the query class to one of:

IN the Internet class

CH the Chaos class

HS the Hesiod class

ANY wildcard

The class specifies the protocol group of the
information. The default is IN; the abbreviation for
this keyword is cl.

nodebug
This keyword turns on or off the display of the full
response packet, and any intermediate response packets,
when searching. The default for this keyword is
nodebug; the abbreviation for this keyword is [no]deb.

nod2 This keyword turns debugging mode on or off. This
displays more about what nslookup is doing. The default
is nod2.

domain=name
This keyword sets the search list to name.

nosearch
If the lookup request contains at least one period, but
does not end with a trailing period, this keyword
appends the domain names in the domain search list to
the request until an answer is received. The default is
search.

port=value
This keyword changes the default TCP/UDP name server
port to value from its default, port 53. The
abbreviation for this keyword is po.

querytype=value | type=value
This keyword changes the type of the information query
to value. The defaults are A and then AAAA; the
abbreviations for these keywords are q and ty.

Please note that it is only possible to specify one
query type. Only the default behavior looks up both
when an alternative is not specified.

norecurse
This keyword tells the name server to query other
servers if it does not have the information. The
default is recurse; the abbreviation for this keyword
is [no]rec.

ndots=number
This keyword sets the number of dots (label separators)
in a domain that disables searching. Absolute names
always stop searching.

retry=number
This keyword sets the number of retries to number.

timeout=number
This keyword changes the initial timeout interval to
wait for a reply to number, in seconds.

novc This keyword indicates that a virtual circuit should
always be used when sending requests to the server.
novc is the default.

nofail This keyword tries the next nameserver if a nameserver
responds with SERVFAIL or a referral (nofail), or
terminates the query (fail) on such a response. The
default is nofail.

RETURN VALUES

nslookup returns with an exit status of 1 if any query failed, and 0
otherwise.

IDN SUPPORT

If nslookup has been built with IDN (internationalized domain name)
support, it can accept and display non-ASCII domain names. nslookup
appropriately converts character encoding of a domain name before
sending a request to a DNS server or displaying a reply from the
server. To turn off IDN support, define the IDN_DISABLE environment
variable. IDN support is disabled if the variable is set when
nslookup runs, or when the standard output is not a tty.

FILES

/etc/resolv.conf

SEE ALSO

dig(1), host(1), named(8).

AUTHOR

Internet Systems Consortium

COPYRIGHT

2025, Internet Systems Consortium

9.18.34 2025-02-11 NSLOOKUP(1)