nslookup - query name servers interactively
nslookup [ host-to-find | - [ server address | server name ]]
Nslookup is a program to query DARPA Internet domain name servers. Nslookup has two
modes: interactive and non-interactive. Interactive mode allows the user to query the
name server for information about various hosts and domains or print a list of hosts in
the domain. Non-interactive mode is used to print just the name and Internet address of a
host or domain.
Interactive mode is entered in the following cases:
a) when no arguments are given (the default name server will be used), and
b) when the first argument is a hyphen (-) and the second argument is the host name of a
Non-interactive mode is used when the name of the host to be looked up is given as the
first argument. The optional second argument specifies a name server.
Commands may be interrupted at any time by typing a control-C. To exit, type a control-D
(EOF). The command line length must be less than 80 characters. N.B. an unrecognized
command will be interpreted as a host name.
Look up information for host using the current default server or using server if it
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 sri-nic.arpa is used. (This command is a synonym for the
lserver sri-nic.arpa.) The name of the root server can be changed with the set
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 re-
direct output in the usual manner.
ls domain [> filename]
ls domain [>> filename]
ls -a domain [> filename]
ls -a domain [>> filename]
ls -h domain [> filename]
ls -h domain [>> filename]
ls -d domain [> filename]
List the information available for domain. The default output contains host names
and their Internet addresses. The -a option lists aliases of hosts in the domain.
The -h option lists CPU and operating system information for the domain. The -d
option lists all contents of a zone transfer. When output is directed to a file,
hash marks are printed for every 50 records received from the server.
Sorts and lists the output of previous ls command(s) with more(1).
? Prints a brief summary of commands.
This command is used to change state information that affects the lookups. Valid
all Prints the current values of the various options to set. Information about
the current default server and host is also printed.
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)
[no]d2 Turn exhaustive debugging mode on. Essentially all fields of every packet
(Default = nod2)
Append the default domain name to every lookup.
(Default = defname, abbreviation = [no]def)
With defname, search for each name in parent domains of the current domain.
(Default = search)
Change the default domain name to name. The default domain name is appended
to all lookup requests if the defname option has been set. The search list
is set to parents of the domain with at least two components in their names.
(Default = value in hostname or /etc/resolv.conf, abbreviation = do)
Change the type of information returned from a query to one of:
A the host's Internet address (the default).
CNAME the canonical name for an alias.
HINFO the host CPU and operating system type.
MD the mail destination.
MX the mail exchanger.
MG the mail group member.
MINFO the mailbox or mail list information.
MR the mail rename domain name.
NS nameserver for the named zone.
Other types specified in the RFC883 document are valid but aren't very useful.
(Abbreviation = q)
Tell the name server to query other servers if it does not have the informa-
(Default = recurse, abbreviation = [no]rec)
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
request is resent. The retry value controls how many times a request is
resent before giving up.
(Default = 2, abbreviation = ret)
Change the name of the root server to host. This affects the root command.
(Default = sri-nic.arpa, abbreviation = ro)
Change the time-out interval for waiting for a reply to number seconds.
(Default = 10 seconds, abbreviation = t)
[no]vc Always use a virtual circuit when sending requests to the server.
(Default = novc, abbreviation = [no]v)
If the lookup request was not successful, an error message is printed. Possible errors
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
Depending on the query type set with the set querytype command, no information
about the host was available, though the host name is valid.
The host or domain name does not exist.
Network is unreachable
The connection to the name or finger server could not be made at the current time.
This error commonly occurs with finger requests.
The name server found an internal inconsistency in its database and could not
return a valid answer.
The name server refused to service the request.
The following error should not occur and it indicates a bug in the program.
The name server found that the request packet was not in the proper format.
/etc/resolv.conf initial domain name and name server addresses.
resolver(3), resolver(5), named(8), RFC882, RFC883
4.3 Berkeley Distribution November 21, 1987 NSLOOKUP(1)