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NAME    [Toc]    [Back]

     nslookup -- query Internet name servers interactively

SYNOPSIS    [Toc]    [Back]

     nslookup [-option ...] [host-to-find | -[server]]

DESCRIPTION    [Toc]    [Back]

     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

ARGUMENTS    [Toc]    [Back]

     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 directory 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


     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.: 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 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

     root     Changes the default server to the server for the root of the
	      domain name space.  Currently, the host ns.internic.net is used.
	      (This command is a synonym for ``lserver ns.internic.net''.)
	      The name of the root server can be changed with the ``set root''

     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).  The 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

	      -t querytype
		    lists all records of the specified type (see querytype

	      -a    lists aliases of hosts in the domain; synonym for ``-t

	      -d    lists all records for the domain; synonym for ``-t ANY''.

	      -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


     ?	      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.

		       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)

	      [no] d2  Turn exhaustive debugging mode on.  Essentially all
		       fields of every packet are printed.

		       (Default = nod2)

		       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(@CMD_EXT@),
		       /etc/resolv.conf, or LOCALDOMAIN; abbreviation = do)

		       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 specified.  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(@CMD_EXT@),
		       /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] defname)

	      [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)

		       Change the default TCP/UDP name server port to value.

		       (Default = 53; abbreviation = po)


		       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 Internet
				 address; otherwise, the pointer to other

		       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)

		       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

		       (Default = 4, abbreviation = ret)

		       Change the name of the root server to host.  This
		       affects the ``root'' command.

		       (Default = ns.internic.net.; abbreviation = ro)

		       Change the initial timeout interval for waiting for a
		       reply to number seconds. Each retry doubles the timeout

		       (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    [Toc]    [Back]

     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

     Server failure
	    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.

     Format error
	    The name server found that the request packet was not in the
	    proper format.  It may indicate an error in nslookup.

FILES    [Toc]    [Back]

     /etc/resolv.conf		       initial domain name and name server
     $HOME/.nslookuprc		       user's initial options
     /usr/share/misc/nslookup.help     summary of commands

ENVIRONMENT    [Toc]    [Back]

     HOSTALIASES      file containing host aliases
     LOCALDOMAIN      overrides default domain

SEE ALSO    [Toc]    [Back]

     @INDOT@named(@SYS_OPS_EXT@), resolver(@LIB_NETWORK_EXT@),
     resolver(@FORMAT_EXT@); RFC-1034, ``Domain Names - Concepts and
     Facilities''; RFC-1035, ``Domain Names - Implementation and

AUTHOR    [Toc]    [Back]

     Andrew Cherenson

4th Berkeley Distribution	 June 24, 1990	     4th Berkeley Distribution
[ Back ]
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