


NSLOOKUP(8)           MAINTENANCE COMMANDS            NSLOOKUP(8)



NAME
     nslookup - query Internet name servers interactively

SYNOPSIS
     nslookup [ -_o_p_t_i_o_n ... ] [ _h_o_s_t-_t_o-_f_i_n_d | - [ _s_e_r_v_e_r ]]

DESCRIPTION
     _N_s_l_o_o_k_u_p 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 direc-
     tory 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:
9          nslookup -query=hinfo  -timeout=10
9
INTERACTIVE COMMANDS
     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.
9
     _h_o_s_t [_s_e_r_v_e_r]
          Look up information for _h_o_s_t using the current  default
          server  or  using  _s_e_r_v_e_r  if specified.  If _h_o_s_t is an



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9


NSLOOKUP(8)           MAINTENANCE COMMANDS            NSLOOKUP(8)



          Internet address and the query type is A  or  PTR,  the
          name  of  the  host is returned.  If _h_o_s_t 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 _d_o_m_a_i_n
     lserver _d_o_m_a_i_n
          Change the default server to _d_o_m_a_i_n. Lserver  uses  the
          initial  server  to  look  up  information about _d_o_m_a_i_n
          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 [_n_a_m_e] [> _f_i_l_e_n_a_m_e]
     finger [_n_a_m_e] [>> _f_i_l_e_n_a_m_e]
          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).  _N_a_m_e is optional. >
          and >> can be used to  redirect  output  in  the  usual
          manner.


     ls [_o_p_t_i_o_n] _d_o_m_a_i_n [> _f_i_l_e_n_a_m_e]
     ls [_o_p_t_i_o_n] _d_o_m_a_i_n [>> _f_i_l_e_n_a_m_e]
          List the information available for  _d_o_m_a_i_n,  optionally
          creating  or appending to _f_i_l_e_n_a_m_e.  The default output
          contains  host  names  and  their  Internet  addresses.
          _O_p_t_i_o_n can be one of the following:

          -t _q_u_e_r_y_t_y_p_e
              lists  all  records  of  the  specified  type  (see
              _q_u_e_r_y_t_y_p_e below).

          -a  lists aliases of hosts in the domain.  synonym  for
              -t  CNAME.

          -d  lists all records  for  the  domain.   synonym  for
              -t  ANY.




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          -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 _f_i_l_e_n_a_m_e
          Sorts and lists the output of  previous  ls  command(s)
          with _m_o_r_e(1).


     help

     ?    Prints a brief summary of commands.


     exit Exits the program.


     set _k_e_y_w_o_r_d[=_v_a_l_u_e]
          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=_v_a_l_u_e
               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



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               all fields of every packet are printed.
               (Default = nod2)

          domain=_n_a_m_e
               Change  the  default  domain  name  to  _n_a_m_e.  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)

          srchlist=_n_a_m_e_1/_n_a_m_e_2/...
               Change the default domain name to  _n_a_m_e_1  and  the
               domain search list to _n_a_m_e_1, _n_a_m_e_2, etc. A maximum
               of 6 names separated by slashes (/) can be  speci-
               fied.  For example,
9                   set srchlist=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU
9               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)

          [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=_v_a_l_u_e
               Change the default TCP/UDP  name  server  port  to
               _v_a_l_u_e.
               (Default = 53, abbreviation = po)

          querytype=_v_a_l_u_e



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          type=_v_a_l_u_e
               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  Inter-
                         net  address,  otherwise  the pointer to
                         other information.

               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)

          retry=_n_u_m_b_e_r
               Set the number of retries to _n_u_m_b_e_r. 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)

          root=_h_o_s_t
               Change the name of the root server to  _h_o_s_t.  This
               affects the root command.
               (Default = ns.internic.net., abbreviation = ro)

          timeout=_n_u_m_b_e_r



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               Change the initial timeout  interval  for  waiting
               for  a reply to _n_u_m_b_e_r 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 certain
          amount  of  time (changed with set timeout=_v_a_l_u_e) and a
          certain   number   of   retries   (changed   with   set
          retry=_v_a_l_u_e).

     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 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.

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



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          _n_s_l_o_o_k_u_p.


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), in.named(8),
     RFC-1034  ``Domain Names - Concepts and Facilities''
     RFC-1035  ``Domain Names  -  Implementation  and  Specifica-
     tion''

AUTHOR
     Andrew Cherenson


































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