nslookup

NSLOOKUP(1)                         BIND 9                         NSLOOKUP(1)

NAME
       nslookup - query Internet name servers interactively

SYNOPSIS
       nslookup [-option] [name | -] [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
       prints 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 is 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 sec-
       ond argument specifies the host name or address of a name server.

       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, with an initial timeout  of  10
       seconds, type:

          nslookup -query=hinfo  -timeout=10

       The -version option causes nslookup to print the version number and im-
       mediately exit.

INTERACTIVE COMMANDS
       host [server]
              This command looks up information for host using the current de-
              fault server or using server, if specified. If host is an Inter-
              net 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 pe-
              riod (.), the search list is used to qualify the name.

              To look up a host not in the current domain, append a period  to
              the name.

       server domain | lserver domain
              These commands 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 an-
              swer cannot be found, the names of servers that might  have  the
              answer are returned.

       root   This command is not implemented.

       finger This command is not implemented.

       ls     This command is not implemented.

       view   This command is not implemented.

       help   This command is not implemented.

       ?      This command is not implemented.

       exit   This command exits the program.

       set keyword[=value]
              This  command  is  used to change state information that affects
              the lookups. Valid keywords are:

              all    This keyword prints the current values of the  frequently
                     used  options  to  set. Information about the current de-
                     fault server and host is also printed.

              class=value
                     This keyword changes the query class to one of:

                     IN     the Internet class

                     CH     the Chaos class

                     HS     the Hesiod class

                     ANY    wildcard

                     The class specifies the protocol group  of  the  informa-
                     tion.  The  default is IN; the abbreviation for this key-
                     word is cl.

              nodebug
                     This keyword turns on or off the display of the full  re-
                     sponse  packet,  and  any  intermediate response packets,
                     when searching. The default for this keyword is  nodebug;
                     the abbreviation for this keyword is [no]deb.

              nod2   This  keyword  turns  debugging mode on or off. This dis-
                     plays more about what nslookup is doing. The  default  is
                     nod2.

              domain=name
                     This keyword sets the search list to name.

              nosearch
                     If  the  lookup request contains at least one period, but
                     does not end with a trailing period, this keyword appends
                     the domain names in the domain search list to the request
                     until an answer is received. The default is search.

              port=value
                     This keyword changes the default TCP/UDP name server port
                     to  value from its default, port 53. The abbreviation for
                     this keyword is po.

              querytype=value | type=value
                     This keyword changes the type of the information query to
                     value.  The  defaults  are A and then AAAA; the abbrevia-
                     tions for these keywords are q and ty.

                     Please note that it is only possible to specify one query
                     type. Only the default behavior looks up both when an al-
                     ternative is not specified.

              norecurse
                     This keyword tells the name server to query other servers
                     if  it  does not have the information. The default is re-
                     curse; the abbreviation for this keyword is [no]rec.

              ndots=number
                     This keyword sets the number of dots  (label  separators)
                     in  a  domain that disables searching. Absolute names al-
                     ways stop searching.

              retry=number
                     This keyword sets the number of retries to number.

              timeout=number
                     This keyword changes the initial timeout interval to wait
                     for a reply to number, in seconds.

              novc   This  keyword indicates that a virtual circuit should al-
                     ways be used when sending requests to the  server.   novc
                     is the default.

              nofail This  keyword  tries  the next nameserver if a nameserver
                     responds with SERVFAIL or a referral (nofail), or  termi-
                     nates the query (fail) on such a response. The default is
                     nofail.

RETURN VALUES
       nslookup returns with an exit status of 1 if any query  failed,  and  0
       otherwise.

IDN SUPPORT
       If  nslookup  has  been  built with IDN (internationalized domain name)
       support, it can accept and display non-ASCII domain names. nslookup ap-
       propriately converts character encoding of a domain name before sending
       a request to a DNS server or displaying a reply from  the  server.   To
       turn  off IDN support, define the IDN_DISABLE environment variable. IDN
       support is disabled if the variable is set when nslookup runs, or  when
       the standard output is not a tty.

FILES
       /etc/resolv.conf

SEE ALSO
       dig(1), host(1), named(8).

AUTHOR
       Internet Systems Consortium

COPYRIGHT
       2025, Internet Systems Consortium

9.18.30-0ubuntu0.20.04.2-Ubuntu   2024-09-09                       NSLOOKUP(1)