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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP Administration and Troubleshooting Utilities and Protocols

TCP/IP DNS Name Resolution and Information Lookup Utilities (nslookup, host and dig) 1 2 3 TCP/IP Network Status Utility (netstat)

Third-Party whois Tools

Many operating systems, including Windows, do not come with a whois command implementation, but there are third-party programs that will support the function. In recent years many different organizations have also set up Web sites that implement the whois function, which is much more convenient and user-friendly to those more accustomed to graphical operating systems like Windows. Many of these sites are provided as free services by DNS registrars, so customers can check if a name they are interested in is already taken, and if so, by whom.

One drawback of some of these systems is that they usually do not have the intelligence to check all the different registries where domain name records are stored. In most cases, a whois service provided by a registrar will only search for names in the particular top-level domains (TLDs) in which the registrar operates. So, if the registrar deals with .COM, .ORG and .NET, it may only support whois queries for those TLDs. To check the registration information for domains in more obscure TLDs, such as some of the less common geopolitical (country code) domains, a considerable amount of searching may be required.

TCP/IP DNS Name Resolution and Information Lookup Utilities (nslookup, host and dig) 1 2 3 TCP/IP Network Status Utility (netstat)