#nslookup

NSLOOKUP(1)                                      BIND9                                     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 is used to print just the name and requested information for a host or       domain.

ARGUMENTS       Interactive mode is entered in the following cases:

       1. when no arguments are given (the default name server will be used)

       2. 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.

      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

      The -version option causes nslookup to print the version number and immediately exits.

INTERACTIVE COMMANDS       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 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           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           not implemented

      finger           not implemented

      ls           not implemented

      view           not implemented

      help           not implemented

      ?           not implemented

      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

              CH                   the Chaos class

              HS                   the Hesiod class

              ANY                   wildcard

              The class specifies the protocol group of the information.

              (Default = IN; abbreviation = cl)

          [no]debug               Turn on or off the display of the full response packet and any intermediate response               packets when searching.

              (Default = nodebug; abbreviation = [no]deb)

          [no]d2               Turn debugging mode on or off. This displays more about what nslookup is doing.

              (Default = nod2)

          domain=name               Sets the search list to name.

          [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)

          port=value               Change the default TCP/UDP name server port to value.

              (Default = 53; abbreviation = po)

          querytype=value

          type=value               Change the type of the information query.

              (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)

          ndots=number               Set the number of dots (label separators) in a domain that will disable searching.               Absolute names always stop searching.

          retry=number               Set the number of retries to number.

          timeout=number               Change the initial timeout interval for waiting for a reply to number seconds.

          [no]vc               Always use a virtual circuit when sending requests to the server.

              (Default = novc)

          [no]fail               Try the next nameserver if a nameserver responds with SERVFAIL or a referral (nofail)               or terminate query (fail) on such a response.

              (Default = nofail)

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

FILES       /etc/resolv.conf

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

AUTHOR       Internet Systems Consortium, Inc.

COPYRIGHT       Copyright © 2004-2007, 2010, 2013-2017 Internet Systems Consortium, Inc. ("ISC")

Came across this this nifty trick, courtesy of SuperUser. Here's a way to find out your public IP address via a DNS query:

nslookup / windows:

nslookup myip.opendns.com. resolver1.opendns.com

dig / Linux:

dig +short myip.opendns.com @resolver1.opendns.com