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nslookup(8)							   nslookup(8)

       nslookup - Queries Internet name servers interactively

       Noninteractive Mode

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

       Interactive Mode

       nslookup [-option ...] [- server]

       The nslookup command is a program that is used to query Internet domain
       name servers.  The nslookup command has two modes: interactive and non‐
       interactive.   Noninteractive  mode  is used to print just the name and
       requested information for a host or  domain.   Noninteractive  mode  is
       invoked	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  hostname or address of a name server.  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.  Interactive mode is
       invoked when you specify nslookup without arguments (the	 default  name
       server  will  be	 used),	 or when the first argument you specify is a -
       (dash) and the second argument is the hostname or Internet address of a
       name server.

       The  options  listed under the set command can be specified in the 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 - (dash).  For example, to change  the  default
       query type to host information, and the initial time-out to 10 seconds,
       enter: nslookup -query=hinfo  -timeout=10

   Interactive Commands
       Commands may be interrupted at any time by entering <Ctrl-c>. To	 exit,
       enter <Ctrl-d> (EOF) or type exit. The command line length must be less
       than 256 characters.  To treat a built-in command as a  hostname,  pre‐
       cede  it	 with an escape character \ (backslash). Note that an unrecog‐
       nized command will be interpreted as a hostname.

       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 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 (dot) to the name.  Changes 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.  Changes the default server to the server
       for  the	 root  of the domain name space. Currently, the host ns.inter‐
       nic.net is used. (This command  is  a  synonym  for  lserver  ns.inter‐
       nic.net.)  The name of the root server can be changed with the set root
       command.	 Connects with the finger server on the current host. The cur‐
       rent  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. The> and >> (redirection symbols) can be used to re‐
       direct output in the usual manner.  Lists the information available for
       domain,	optionally creating or appending to filename. The default out‐
       put contains hostnames and their Internet addresses.  option can be one
       of  the	following: Lists all records of the specified type (see query‐
       type later in this reference page).  Lists  aliases  of	hosts  in  the
       domain.	 This option is a synonym for -t CNAME.	 Lists all records for
       the domain.  This option is a synonym for -t ANY.  Lists CPU and	 oper‐
       ating  system  information for the domain. This option is a synonym for
       -t HINFO.  Lists well-known services  of	 hosts	in  the	 domain.  This
       option  is  a synonym for -t WKS.  When output is directed to a file, #
       (number signs) are printed for  every  50  records  received  from  the
       server.	 Sorts	and  lists  the	 output of previous ls command(s) with
       more.  Prints a brief summary of commands.  Exits  the  program.	  This
       command	is  used to change state information that affects the lookups.
       Valid keywords are: Prints the current values of	 the  frequently  used
       options	to set. Information about the  current default server and host
       is also printed.	 Changes the query  class  to  one  of:	 The  Internet
       class.	The  Chaos class.  The MIT Athena Hesiod class.	 Wildcard (any
       of the above).  The class specifies the protocol group of the  informa‐
       tion.  (Default = IN, abbreviation = cl) Turns 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) Turns
       exhaustive debugging mode on. Essentially all fields  of	 every	packet
       are  printed. (Default = nod2) Changes 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  com‐
       ponents	in  its	 name. For example, if the default domain is CC.Berke‐
       ley.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 com‐
       mand  to	 display  the  list.   (Default	  =   value   from   hostname,
       /etc/resolv.conf or LOCALDOMAIN, abbreviation = do) Changes the default
       domain name to name1 and the domain search list to name1, name2, and so
       on. 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  dis‐
	      play   the   list.   (Default   =	  value	  based	 on  hostname,
	      /etc/resolv.conf or LOCALDOMAIN, abbreviation = srchl)  If  set,
	      appends  the  default  domain  name to a single-component lookup
	      request (that is, one that does not contain a dot).  (Default  =
	      defname,	abbreviation = [no]def) If the lookup request contains
	      at least one (dot) but does not end with a trailing dot, appends
	      the  domain names in the domain search list to the request until
	      an  answer  is  received.	 (Default  =  search,  abbreviation  =
	      [no]sea)	Changes the default TCP/UDP name server port to value.
	      (Default = 53, abbreviation = po) Changes the type  of  informa‐
	      tion  query to one of: The host's IPv4 address.  The host's IPv6
	      address.	The canonical name for an alias.   The	host  CPU  and
	      operating	 system	 type.	 The mailbox or mail list information.
	      The mail exchanger.  The Naming AUthority PoinTeR that  contains
	      rules  for  mapping parts of Uniform Resource Identifiers (URIs)
	      to domain names.	The name server for the named zone.  The host‐
	      name  if the query is an Internet address; otherwise the pointer
	      to other information.  The domain's start-of-authority  informa‐
	      tion.   The host that can provide a specific resolution service.
	      The text information.   The  user	 information.	The  supported
	      well-known  services.  Other types (ANY, AXFR, MB, MD, MF, NULL)
	      are described in the RFC1035 document. (Default =	 A,  abbrevia‐
	      tions  =	q, ty) Tells the name server to query other servers if
	      it does not have the information.	 (Default = recurse, abbrevia‐
	      tion  =  [no]rec)	 Sets  the number of retries to number. When a
	      reply to a request is not received within a  certain  amount  of
	      time  (changed with set time-out), 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, abbre‐
	      viation = ret) Changes the name of  the  root  server  to	 host.
	      This  affects  the  root	command.  (Default = ns.internic.net.,
	      abbreviation = ro) Changes  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 server.
	      (Default = novc, abbreviation = [no]v) Ignore packet  truncation
	      errors. (Default = noignoretc, abbreviation = [no]ig)

       In  noninteractive  mode,  nslookup  can return the following values: A
       match was found.	 No match was found, or an error occurred.

       If the lookup request was not successful, an error message is  printed.
       Possible	 errors	 are:  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 name server is
       running on the server machine.	The  server  does  not	have  resource
       records	of  the current query type for the host, although the hostname
       is valid. The query type is specified with the set  querytype  command.
       The  host or domain name does not exist.	 The connection to the name or
       finger server could not be made at the current time.  This  error  com‐
       monly  occurs  with  ls	and 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 name
       server found that the request packet was not in the proper  format.  It
       may indicate an error in nslookup.

       Specifies  the  command	path  Initial  domain  name  and  name	server
       addresses User's initial options Summary of commands

       Commands: named(8)

       Functions: resolver(4)

       Files: resolv.conf(4)

       Specifications:	RFC1034, RFC1035


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