Introduced 1985
TLD type Country code top-level domain
Status Active
Registry Nominet UK
Sponsor Nominet UK
Intended use Entities connected with the
United Kingdom United Kingdom
Actual use Very popular in UK, especially .co.uk subdomain
Registered domains 9,627,873 (August 2011)[1]
Registration restrictions It is prohibited to register a domain name directly under the ccTLD .uk. No restrictions for .co.uk, .me.uk, and .org.uk; other subdomains have differing restrictions
Structure At third level, beneath generic-category 2nd level domains, except under .sch.uk where registration is at fourth level; no second-level registrations (a few old registrations grandfathered)
Dispute policies DRS Policy
Website nic.uk

.uk is the Internet country code top-level domain (ccTLD) for the United Kingdom. As of August 2011, it is the fourth most popular top-level domain worldwide (after .com, .de and .net), with over 9.5 million registrations.[2]

The use of .uk rather than .gb for the top-level domain is due to its pre-existing use in the (now obsolete) JANET Name Registration Scheme in which the order of address components were reversed. .uk was made available in DNS to simplify the translation to and from these addresses. There were plans for eventual transition to .gb to accord with correct usage, but this never occurred; the use of .uk is now entrenched, and it is impossible to register a .gb domain.

Unusually, the '.co.uk' second-level domain within '.uk' is more widely used than for most other countries where the ccTLD has primacy. This is a result of specific rules set by Nominet, the UK's naming body, prohibiting direct use of the ccTLD. The Nominet website itself is formally no exception to this rule, however, the second level domain it uses "nic.uk" is not open to public registration.

It uses OpenDNSSEC.



As with other ccTLDs in the early days it was originally delegated to an individual by Jon Postel. In time, it passed to Dr Willie Black at the UK Education and Research Networking Association. Originally, Domain requests were emailed, manually screened by and then forwarded to the UK Naming Committee before being processed by UKERNA. Membership of this Committee was restricted to a group of high-end ISPs who were part of a formal peering arrangement.

The Naming Committee was organised as a mailing list to which all proposed names were circulated. The members would consider the proposals under a ruleset that insisted that all domain names should be very close if not identical to a registered business name of the registrant. Members of the Naming Committee could object to any name, and if a small number of objections were received, the name was refused.

By the mid-1990s the growth of the Internet, and particularly the advent of the World Wide Web was pushing requests for domain name registrations up to levels that were not manageable by a group of part-time voluntary managers. Oliver Smith of Demon Internet forced the issue by providing the committee with a series of automated tools, called the "automaton", which formalised and automated the naming process end to end. This allowed many more registrations to be processed far more reliably and rapidly, and inspired individuals such as Ivan Pope to explore more entrepreneurial approaches to registration.

Various plans were put forward for the possible management of the domain, mostly Internet service providers seeking to stake a claim, each of which were naturally unacceptable to the rest of the committee. In response to this Dr Black, as the .uk Name, stepped up with a bold proposal for a not-for-profit commercial entity to deal with the .uk domain properly. Commercial interests initially balked at this, but with widespread support Nominet UK was formed in 1996 to be the .uk Network Information Centre, a role which it continues to this day.

The general form of the rules (i.e. which domains can be registered and whether to allow second level domains) was set by the Naming Committee. Nominet has not made major changes to the rules, although it has introduced a new second level domain .me.uk for individuals.

It is prohibited to register a domain name directly under .uk (such as internet.uk) and a second-level domain must be used (such as internet.co.uk).

However, some domains delegated before the creation of Nominet UK remain. Examples include mod.uk (Ministry of Defence), parliament.uk (Parliament), bl.uk and british-library.uk (the British Library), nls.uk (the National Library of Scotland), nhs.uk (The National Health Service), and jet.uk (UKAEA as operator of the Joint European Torus experimental fusion tokamak). No new 'normal' registrations at the second level are accepted although there is a system for allocating new second level domains to expand the capacity of the system. Such allocations are rarely made.

It is possible to directly register a domain name with Nominet UK but it is faster and cheaper to do it via a Nominet Registrar.

Second-level domains

Rejected second-level domains

  • .soc.uk - proposed for Social and Society use.
  • .cym.uk - A domain for Wales; it did not have support of the Welsh internet community, with a .cym domain being proposed.
  • .scot.uk - A domain for Scotland; it did not have the support of the Scottish internet community, with .sco domain being proposed.

Individual institutions

Inactive second-level domains

.co.uk, .ltd.uk, .me.uk, .net.uk, .nic.uk, .org.uk, .plc.uk and .sch.uk are managed by Nominet UK and except for .nic.uk are available for registration by the public (though they all carry various degrees of restrictions). The other second-level domains are managed by various government agencies, and generally more strongly controlled.

Allocation of domain names

Allocations are on a strict first-come, first-served basis to qualified applicants. There are no territorial restrictions: applicants need not have any connection to the UK other than those outlined below for .ltd.uk and other restricted domains.

.co.uk is by far the most used of the domains, followed by .org.uk then .me.uk. .plc.uk and .ltd.uk are only rarely used. The number of new registrations for each of the different .uk domains on a month by month basis can be seen on the Nominet website (www.nominet.org.uk/intelligence/statistics/registration/)

The intended restriction of .co.uk to companies is purely nominal; in practice it is open to any and all applicants. Likewise, whilst .org.uk is for organizations, there are no restrictions on registering domains. While .me.uk originally had no restrictions on registrants it has since been tightened up to require registrants to be natural persons (i.e. not companies, etc.).

However, registrants in .ltd.uk must be, and remain, private limited companies incorporated under the UK Companies Acts. In addition, names can only be registered if they correspond (in accordance with the algorithm in the rules of registration) with the exact company name, as recorded at the companies registry at Companies House. The same conditions apply for .plc.uk, but for public limited companies. Neither of these domains is widely used.

.net.uk is more open, but the Nominet regulations still mean that a registrant must be an ISP, or a similar body, and that the domain is not used for providing services to end-users. .nic.uk, however, is limited solely to domains operated by Nominet.

.ac.uk domains are intended for the use of higher education institutions (beyond compulsory education age), and are also used by some academic support bodies such as the Universities and Colleges Admissions Service (www.ucas.ac.uk), public research establishments, and learned societies such as the Royal Society (royalsoc.ac.uk). Primary and secondary education uses .sch.uk.


Unusually, .sch.uk domains are allocated at the fourth level, with the third level being taken up by the name of the local authority (LA, previously LEA or Local Education Authority) e.g. schoolname.leaname.sch.uk. For example, The Campion School in Hornchurch has the domain name http://www.campion.havering.sch.uk/,[4] and West Exe Technology College in Exeter has the domain name http://www.westexetc.devon.sch.uk. Previously applications were made in the normal way, but after Nominet came to an arrangement with the education authorities, one domain per school was issued automatically.

See also

  • .cym
  • .eng
  • .gb
  • .sco


  1. ^ http://www.nominet.org.uk/intelligence/statistics/registration/
  2. ^ (German) DENIC eG - Comparison of international Domain Numbers
  3. ^ The registration process and a list of domain names for the .police.uk domain was released by the National Policing Improvement Agency under a Freedom of Information request on 10 March 2009.
  4. ^ "Campion School Havering". Archived from the original on 2009-06-01. http://www.campion.havering.sch.uk. Retrieved 2009-05-30. 

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