nslookup(1) - phpMan

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: in-
teractive 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 In-
ternet 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 us-
ing 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 trail-
ing 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 key-
word 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 de-
faults 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 de-
fault 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 key-
word 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 SERV-
FAIL or a referral (nofail), or terminates the query (fail) on such a re-
sponse. 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