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Top-level domains

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Top-level domains

The following is a list of the eight top-level domains most often used on the Internet to classify organizations by type when they register a second-level domain name for use. For example, (the second-level domain name registered to Microsoft) is registered in the "com" domain, because this is the top-level domain provided for organizations that do business (commerce) on the Internet.


Top-level name Description Used by


Owned by Advanced Research Project Agency (ARPA). Used to register reverse mapping of Internet Protocol (IP) version 4 (IPv4) and IP version 6 (IPv6) addresses assigned by the Internet Assigned Number Authority (IANA) to Domain Name System (DNS) domain names for computers that use those addresses on the Internet.

The domain, the domain


For business and commercial use.

Businesses and corporations


For educational use.

Public and private schools, colleges, and universities


For use by governmental institutions.

Local, state, and federal government agencies


Reserved for international use. Originally planned for use in RFC 1886 to register reverse mapping of IPv6 addresses. For more information about RFCs, see DNS RFCs.



For use by military agencies.

Department of Defense (DoD), U.S. Navy, U.S. Army, U.S. Air Force, and other military agencies


For use by organizations that provide large-scale Internet or telephony-based service.

InterNIC, AT&T, and other large-scale Internet and telephone service providers


For use by noncommercial, nonprofit organizations.

Churches and charitable institutions


  • In addition to these top-level domains which are all three letters in length, the use of two-letter country/region codes (such as "uk" for United Kingdom) are reserved for use. These country/region codes can also be used in conjunction with the three-letter codes listed above to further specify the country or region of origin for organizations that register names in the Internet DNS namespace.

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