


NSLOOKUP(8)                                           NSLOOKUP(8)


NAME
       nslookup - query Internet name servers interactively

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

DESCRIPTION
       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 domain.


ARGUMENTS
       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

INTERACTIVE COMMANDS
       Commands  may  be interrupted at any time by typing a con-
       trol-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 com-
       mand 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



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NSLOOKUP(8)                                           NSLOOKUP(8)


              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
              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  syn-
              onym for lserver ns.internic.net.)  The name of the
              root server can be changed with the set  root  com-
              mand.


       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  com-
              mand).   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,  option-
              ally   creating  or  appending  to  filename.   The
              default output contains host names and their Inter-
              net 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.



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NSLOOKUP(8)                                           NSLOOKUP(8)


              -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 com-
              mand(s) with PAGER if it is defined  and  non-null,
              or with more(1) otherwise.


       help

       ?      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.

              class=value
                     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  informa-
                     tion 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.   Essen-
                     tially   all  fields  of  every  packet  are



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NSLOOKUP(8)                                           NSLOOKUP(8)


                     printed.
                     (Default = nod2)

              domain=name
                     Change the default domain name to name.  The
                     default  domain name is appended to a lookup
                     request depending on the state of  the  def-
                     name  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 dif-
                     ferent list.  Use the  set  all  command  to
                     display the list.
                     (Default     =    value    from    hostname,
                     /etc/resolv.conf or  LOCALDOMAIN,  abbrevia-
                     tion = do)

              srchlist=name1/name2/...
                     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 srch-
                     list=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU
                     sets  the  domain  to  lcs.MIT.EDU  and  the
                     search list to the three names.   This  com-
                     mand  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,  abbrevia-
                     tion = 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]def)

              [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)

              port=value
                     Change  the default TCP/UDP name server port
                     to value.
                     (Default = 53, abbreviation = po)



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NSLOOKUP(8)                                           NSLOOKUP(8)


              querytype=value
              type=value
                     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  informa-
                               tion.

                     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-author-
                               ity'' 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)

              retry=number
                     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 con-
                     trols  how  many  times  a request is resent
                     before giving up.
                     (Default = 4, abbreviation = ret)

              root=host
                     Change the name of the root server to  host.



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NSLOOKUP(8)                                           NSLOOKUP(8)


                     This affects the root command.
                     (Default  = ns.internic.net., abbreviation =
                     ro)

              timeout=number
                     Change  the  initial  timeout  interval  for
                     waiting for a reply to number seconds.  Each
                     retry doubles the timeout period.
                     (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
       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 cer-
            tain 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 cur-
            rent  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 requests.

       Server failure
            The  name  server  found an internal inconsistency in
            its database and could not return a valid answer.

       Refused
            The name server refused to service the request.




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NSLOOKUP(8)                                           NSLOOKUP(8)


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


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

ENVIRONMENT
       HOSTALIASES    file containing host aliases.
       LOCALDOMAIN    overrides default domain.

SEE ALSO
       resolver(3), resolver(5), named(8),
       RFC-1034  ``Domain Names - Concepts and Facilities''
       RFC-1035   ``Domain  Names - Implementation and Specifica-
       tion''

AUTHOR
       Andrew Cherenson

































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