Second-level domain

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In the Domain Name System (DNS) hierarchy, a second-level domain (SLD) is a domain that is directly below a top-level domain (TLD). For example, in example.com, example is the second-level domain of the .com TLD.

Second-level domains commonly refer to the organization that registered the domain name with a domain name registrar. Some domain name registries introduce a second-level hierarchy to a TLD that indicates the type of entity intended to register an SLD under it. For example, in the .uk namespace a college or other academic institution would register under the .ac.uk ccSLD, while companies would register under .co.uk.


Country-code second-level domains[edit]

Australia[edit]

In Australia, currently there are 16 active second-level domains, all managed by auDA.[1]

Open second-level domains (available for the public):

  • .asn.au - for associations, political parties and clubs.
  • .com.au - for commercial use.
  • .net.au - for registered companies.
  • .id.au - for Australian citizens only.
  • .org.au - For non-profit organisations.

Closed second-level domains (restricted to certain sectors):

  • .edu.au - for academic institutions.
  • .gov.au - for government bodies.
  • .csiro.au - for the Commonwealth Science and Industry Research Organisation (CSIRO). The domain is administrated by CSIRO itself.

Community Geographic Domain Names (restricted to certain geographic regions for community use):

  • .act.au for the Australian Capital Territory.
  • .nsw.au for New South Wales.
  • .nt.au for the Northern Territory.
  • .qld.au for Queensland.
  • .sa.au for South Australia.
  • .tas.au for Tasmania.
  • .vic.au for Victoria.
  • .wa.au for Western Australia.[2]

Historically, Australia's country code top-level domain was .oz. After the introduction of the .au ccTLD, the domains in .oz were moved under the oz.au second-level domain.[3]

Austria[edit]

In Austria there are two second-level domains available for the public: .co.at intended for commercial enterprises and .or.at intended for organizations.[4] The second-level domain .priv.at is restricted to Austrian citizens only, while .ac.at and .gv.at are reserved for educational insitutions and governmental bodies respectively.[5][6]

France[edit]

In France, there are various second-level domains available for certain sectors, including .avocat.fr for attorneys, .aeroport.fr for airports and .veterinaire.fr for vets.[7]

Hungary[edit]

There are 21 active second-level domains in Hungary, including: .co.hu, .film.hu, .lakas.hu, .ingatlan.hu,.sport.hu and .hotel.hu. The registration of second-level domains is managed by the Council of Hungarian internet providers.[8]

Russia[edit]

Second-level domain registrations are handled jointly by the official registry service CCTLDRU and private companies. There are currently 133 active second-level domains available for registration. This large number is due to the fact that every geographical region has its own second-level domain, such .volgograd.ru for the Volgograd Region, .irkutsks.ru for the Irkutsk region or msk.ru for Moscow. There also second–level domains for specific sectors, such as ac.ru for academic institutions, com.ru for commercial enterprises or int.ru for international organizations.[9]

South Africa[edit]

Under the .za ccTLD there are several second-level domains in use. These include:

  • .ac.za for academic institutions.
  • .gov.za for government departments.
  • .law.za for law firms and attorneys.
  • .mil.za for the Department of Defence
  • nom.za for personal use.[10] The registration is handled by NOM.ZA.[11]and is available for free.[12]
  • .school.za for primary and secondary schools.
  • .net.za for network providers.[13]

Spain[edit]

Spanish second-level domains include .nom.es intended for personal names, .org.es for non-profit organizations and .gob.es for government agencies.[14]

Turkey[edit]

In Turkey, domain registrations, including the registration of second-level domains is administrated by nic.tr.[15] There 17 active second-level domains under the .tr TLD.[16] The registration of domains is restricted to Turkish individuals and businesses, or foreign companies with a business activity in Turkey.[17] Second-level domains include .com.tr for commercial ventures, .edu.tr for academic institutions and .name.tr for personal use.[18]

United Kingdom[edit]

Currently there are 12 active second-level domains under the .uk top-level domain. The majority of the domains is administrated by the UK's domain registry services provider Nominet UK, while the others are managed by the British government. Generally, the registration of uk second-level domains is open to the public, however depending on the second-level domain there might by restrictions – for example .me.uk is open to the public, but .ac.uk is only available to educational institutions.

  • .co.uk - intended for uk based businesses. It is the UK's most widely used second-level domain.
  • .org.uk - intended for non-profit organizations.
  • .me.uk - available only for personal use.
  • .ltd.uk - available only for private limited companies in the UK.
  • .plc.uk – available only for public limited companies in the UK.
  • .net.uk - available only for Internet providers in the UK.
  • .sch.uk - available only for schools in the UK.
  • .ac.uk - intended for British academic institutions.
  • .gov.uk - available for government agencies.
  • .mod.uk and .mil.uk - available for the UK Armed Forces and Ministry of Defence.
  • .nhs.uk - registration restricted to the National Health Service only.
  • .police.uk - reserved for the UK police forces.[19]

Historic second-level domains[edit]

There are several second-level domains which are no longer available.

Australia[edit]

Second-level domains under .au which are no longer available include: .conf.au originally intended for conferences; .gw.au for the Australian Academic and Research networks; info.au for general information, .otc.au and .telememo.au for the X.400 mail systems.[20]

France[edit]

Historic second-level domains for France included: .tm.fr (for brands), .com.fr (for commercial use) and .asso.fr. [21][22]

Yugoslavia[edit]

In 2006 the .yu ccTLD was replaced by rs (for Serbia) and .me (for Montenegro). Second-level domains under .yu included: .ac.yu – for academic institutions, .co.yu for commercial enterprises; .org.yu for organizations and .cg.yu for residents of Montenegro. Only legal entities were allowed to register names under .yu and its second-level domains. [23]

Legal issues[edit]

As a result of ICAANs generic top-level domain (gTLD) expansion,[24] the risk of domain squatting has increased significantly. For example, based on current regulations, the registration of the gTLDs .olympics or .redcross is not allowed, however the registration of sites such as olympics.example or redcross.example is not controlled.[25] Experts say that further restrictions are needed for second-level domains under the new gTLD .health, as well. For example, second-level domains under .tobacco.health or .diet.health can be easily misused by companies and therefore are a potential threat to Internet users.[26]

See also[edit]

References[edit]

  1. ^ "About auDA". Retrieved 29 October 2014. 
  2. ^ ".au Domains". Retrieved 28 October 2014. 
  3. ^ "Old Country-Code Top-Level Internet Domains Never Die, They Just Fade Away (Sometimes)". Retrieved 31 October 2014. 
  4. ^ "Useful information about .or.at domains". Retrieved 29 October 2014. 
  5. ^ "Domain registration". Retrieved 29 October 2014. 
  6. ^ "Principles and Grants". Retrieved 29 October 2014. 
  7. ^ "Sector-based .fr domains". Retrieved 31 October 2014. 
  8. ^ "DELEGATION RULES - SECONDARY LEVEL PUBLIC DOMAINS". Retrieved 29 October 2014. 
  9. ^ "Reserved domain names". Retrieved 29 October 2014. 
  10. ^ "NOM.ZA NameSpace: Conditions of Registration". Retrieved 29 October 2014. 
  11. ^ "2007 September 26: NOM.ZA reply to ZADNA policy". Retrieved 29 October 2014. 
  12. ^ "2007 September 26: NOM.ZA reply to ZADNA policy". Retrieved 29 October 2014. 
  13. ^ "Clarifying ZA SLD Policies". Retrieved 31 October 2014. 
  14. ^ "Country Domain Extensions". Retrieved 31 October 2014. 
  15. ^ "Overview". Retrieved 29 October 2014. 
  16. ^ "Who could register which domain name?". Retrieved 29 October 2014. 
  17. ^ "Can an individual or a company in abroad register a ".tr" domain name?". Retrieved 29 October 2014. 
  18. ^ "Who could register which domain name?". Retrieved 29 October 2014. 
  19. ^ "Second level domains". Retrieved 29 October 2014. 
  20. ^ "the australian second level domain name system". Retrieved 31 October 2014. 
  21. ^ "Useful information about .fr domains". Retrieved 31 October 2014. 
  22. ^ "ICANN-Registrar: French Domains with Accents". Retrieved 31 October 2014. 
  23. ^ ".RS - Republic of Serbia .ME - Republic of Montenegro (Former parts of Yugoslavia) Formerly .YU and .CS Country Codes.". Retrieved 31 October 2014. 
  24. ^ "Delegated strings". Retrieved 29 October 2014. 
  25. ^ Easton, Catherine R. (2012). "ICANN’s core principles and the expansion of generic top-level domain names.". International Journal of Law and Information Technology 20 (4): 273/290. Retrieved 29 October 2014. 
  26. ^ Mackey, TK; Liang, BA; Kohler, JC; Attaran, A (5 March 2014). "Health Domains for Sale: The Need for Global Health Internet Governance". J Med Internet Res 16 (3). doi:10.2196/jmir.3276. PMID 24598602. Retrieved 2014-10-29.