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Creating a WHOIS Lookup Client

In this article we are going to create a whois lookup client application. The main aim of this application will be to look up information about websites on various known WHOIS servers.

Author Info:
By: Jacques Noah
Rating: 5 stars5 stars5 stars5 stars5 stars / 8
September 18, 2006
  1. · Creating a WHOIS Lookup Client
  2. · DNS Resolution
  3. · The Program
  4. · Entire Code

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Creating a WHOIS Lookup Client
(Page 1 of 4 )


Information about websites such as the owner's name, address, domain name, and so on are stored on databases guided by the RFC 954 protocol. In my experience, to access a WHOIS client you need to be on the web with a browser, but with this client all you need is to be connected to the Internet, and you will be able to access website information from the comfort of your desktop.

Because this application is about finding out as much information about a particular domain as possible, I've included another way to get information: DNS resolving. DNS resolving involves finding the IP address by converting a hostname(basically the domain name) to its IP address(es). More on this later. Let's start by explaining what a WHOIS Client is.

What is a WHOIS Client?

A WHOIS client is a program that queries a WHOIS database for information about a particular domain or person. On a technical level, WHOIS is based on a  query/response communication between a client and server. WHOIS is defined in RFC 954, as stated in the introduction, but we do not have a standardized way of retrieving data from a WHOIS database. You can make the following queries with a whois client:

Search by name:

Command line: Smith

Smith     [looks for name or handle SMITH]
         !SRI-NIC  [looks for handle SRI-NIC only]
         .Smith, John
                   [looks for name JOHN SMITH only]

      Adding "..." to the argument will match anything from that point,
      e.g. "ZU..." will match ZUL, ZUM, etc.

Command line: fischer

   Fischer, Charles (CF17)     fischer@UWISC        (608) 262-1204
   Fischer, Herman (HF)        HFischer@USC-ECLB    (818) 902-5139
   Fischer, Jeffery H. (JHF1)  FISCHER@LL-XN        (617) 863-5500
                                                    ext 4403 or 4689
   Fischer, Kenneth (KF8)      SAC.SIUBO@USC-ISIE   (402) 294-5161
                                                    (AV)  271-5161
   Fischer, Marty (MF28)       MFISCHER@DCA-EMS     (703) 437-2344
   Fischer, Michael J. (MJF)   FISCHER@YALE         (203) 436-0744
   Fischer, Nancy C. (NANCY)   FISCHER@SRI-NIC      (415) 859-2539
   Fischer, Richard A. (RAF4)  Fisher Richa@LLL-MFE (415) 422-5032

   To single out any individual entry, repeat the command using the
   argument "!HANDLE" instead of "NAME", where the handle is in
   parentheses following the name. 

To query the full details of a person:
Command line: !nancy

        Fischer, Nancy C. (NANCY)  FISCHER@SRI-NIC SRI International
         Telecommunication Sciences Center
         333 Ravenswood Avenue, EJ289
         Menlo Park, California 94025
         Phone: (415) 859-2539
         MILNET TAC user

Search by mailbox:

         Smith@    [looks for mailboxes with username SMITH]
         @Host     [looks for mailboxes on HOST]
                   [Looks for mailboxes with username SMITH on HOST]

Other than the above specifications, the protocol pretty much leaves it up to us to define how to query a WHOIS database, as well as what kind of information we should include in a WHOIS database.

A WHOIS database contains name server, registrar, and in some cases, full contact information about a domain name. Each registrar must maintain a WHOIS database containing all contact information for the domains they "host." A central registry WHOIS database is maintained by the InterNIC. This database contains only registrar and name server information for all .com, .net and .org domains. Again, the RFC does not specify how much information should be kept about a particular person or registrant. And as a result you get WHOIS databases with  varying levels of information. We are not going to implement the database aspect of the WHOIS in this article, as it is an entire story unto itself.

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