|TLD type||Country code top-level domain|
|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|
The domain was introduced with RFC 920 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. 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.
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.
One .gb subdomain still exists in the DNS (as of 2015[update]):
dra.hmg.gb, belonging to Her Majesty's Government's former Defence Research Agency, and has three known hostnames remaining:
- J. Postel and J. Reynolds (October 1984), Request for Comments: 920, Network Working Group
- Milton Mueller (2002), Ruling the Root: Internet Governance and the Taming of Cyberspace, Cambridge, Massachusetts: MIT Press, p. 79, ISBN 9780262632980
- Crepin-Leblond, Olivier M. J. (2003). "International E-mail Accessibility". Archived from the original on 21 May 2008. Retrieved 23 June 2008.
- "DNS lookup for dra.hmg.gb". 2015. Retrieved 6 March 2015.
- "DNS lookup for hermes.dra.hmg.gb". 2015. Retrieved 6 March 2015.
- "DNS lookup for delos.dra.hmg.gb". 2015. Retrieved 6 March 2015.
- "DNS lookup for dfhnet.dra.hmg.gb". 2015. Retrieved 6 March 2015.
- IANA .gb whois information
- JANET(UK) website
- www.dra.hmg.gb Last accessible copy of www.dra.hmg.gb in the Internet Archive
- Official country code for Britain = GB or UK? Email discussion on GB domain (2002) with historical zonefiles.