From Wikipedia, the free encyclopedia
Jump to: navigation, search
Introduced 1985
TLD type Country code top-level domain
Status Unused
Registry JANET(UK)
Sponsor JANET(UK)
Intended use Entities connected with  United Kingdom
Actual use Fallen into disuse in favour of .uk
Registration restrictions No registrations presently being taken
Structure Government sites formerly found under hmg.gb
Dispute policies None
Website None

.gb is a reserved Internet country code top-level domain (ccTLD) for the United Kingdom.

The domain was introduced with RFC 920[1] in October 1984 that set out the creation of ccTLD generally using country codes derived from the corresponding two-letter code in the ISO 3166-1 list. However, the .uk domain had been created separately a few months before the compilation of this list.[2] Consequently, .gb was never widely used. It is no longer possible to register under this domain.

.gb was used for a number of years, mainly by British government organisations and commercial e-mail services using X.400-based e-mail infrastructure. This simplified translating between DNS domains and X.400 addresses, which used "GB" as a country code.[3]

With the demise of X.400 e-mail and IANA's general aim of one TLD per country, use of .gb declined; the domain remains in existence, but it is not open to new subdomain registrations.

As of 2016, dra.hmg.gb still exists, with at least three subdomains resolving through DNS (although none serve a website): hermes.dra.hmg.gb, delos.dra.hmg.gb, and dfhnet.dra.hmg.gb.[4][5][6] The domain was originally owned by the Defence Research Agency,[7] which became the Defence Evaluation and Research Agency in 1995 and was split into QinetiQ and the Defence Science and Technology Laboratory in 2001; the website became defunct some time thereafter.[8][9]


  1. ^ J. Postel and J. Reynolds (October 1984), Request for Comments: 920, Network Working Group 
  2. ^ Milton Mueller (2002), Ruling the Root: Internet Governance and the Taming of Cyberspace, Cambridge, Massachusetts: MIT Press, p. 79, ISBN 9780262632980 
  3. ^ Crepin-Leblond, Olivier M. J. (2003). "International E-mail Accessibility". Archived from the original on 21 May 2008. Retrieved 23 June 2008. 
  4. ^ "DNS lookup for hermes.dra.hmg.gb". Retrieved 7 March 2016 – via Google Apps Toolbox. 
  5. ^ "DNS lookup for delos.dra.hmg.gb". Retrieved 7 March 2016 – via Google Apps Toolbox. 
  6. ^ "DNS lookup for dfhnet.dra.hmg.gb". Retrieved 7 March 2016 – via Google Apps Toolbox. 
  7. ^ Gollman, Dieter, ed. (November 1994). "A Consideration of the Modes of Operation for Secure Systems". Computer Security – ESORICS 94. Brighton: Springer-Verlag. p. 335. ISBN 3-540-58618-0. 
  8. ^ "DERA". DERA. Archived from the original on 26 May 2001. 
  9. ^ "Page not found". DERA. Archived from the original on 27 March 2002. 

External links[edit]