Domain Names Overview Domain Names are a hierarchical, administratively controlled namespace.   Domain Names provide an easy way for people to refer to a site.

Devices on the Internet are uniquely identified with an Internet Protocol (IP) Number.   IP Numbers (IP version 4) are a set of 4 numbers, each one ranging from 0-255.   (for example; 207.140.138.101)  IP numbers are difficult for people to remember, so many organizations will register a domain names which can be mapped to specific IP Numbers.  For more information about IP numbers see IANA (for example see this allocation of IP numbers)

Today's Domain Name System includes several globally shared domain names  (i.e. .com, .net, .org) as well as many country-specific codes (i.e. .jp, .de, .us, .uk) 

• Domain Name Registration (RFC 1591 - Domain Name System Structure and Delegation)
• Registrar Market Share Statistics.
• Map of Root Domain Server locations.
• An extensive table of Domain name registries around the world (perfect for clients who want to register in other country domains (ISO 3166 - 2 letter Country Codes)
• domain Tools - offers lots of tools including being able to pull up a domain's whois  history.
• Network Solution's Whois [formally "the Internic"] (.COM, .EDU, .NET, and .ORG)
• www.nic.gov
• NIC.MIL
• RPE NCC Registrations in Europe
• APNIC Registrations in Asia-Pacific Rim
• The Internet Corporation for Assigned Names and Numbers
• (ICANN- will now have responsibility for the IP address space allocation, protocol parameter assignment,  domain name system management, and root server system)

For more information see: 

• DNS Resources Directory. - a great site.
• DNS .A sample Chapter from an Oreilly & Associates book - A must read if you want details..
• How DNS Works (from How stuff works)
• Understanding IP Addressing.(pdf)

Note for my Alumni: Your referrals are always appreciated