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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. 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 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.

									Page 1


     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.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 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.

	  -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).

									Page 2



     ?	  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)

	       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)

	       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, /etc/resolv.conf	or
	       LOCALDOMAIN, abbreviation = do)

									Page 3


	       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, /etc/resolv.conf or
	       LOCALDOMAIN, abbreviation = srchl)

	       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)

	       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	information.

	       SOA	 the domain's ``start-of-authority'' information.

	       TXT	 the text information.

									Page 4


	       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)

	       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 up.
	       (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 period.
	       (Default	= 5 seconds, abbreviation = ti)

	       Always use a virtual circuit when sending requests to the
	       (Default	= novc,	abbreviation = [no]v)

	       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.

									Page 5


     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]

     resolver(3), resolver(4), named(1M),
     RFC-1034  ``Domain	Names -	Concepts and Facilities''
     RFC-1035  ``Domain	Names -	Implementation and Specification''

									PPPPaaaaggggeeee 6666
[ Back ]
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