Second-level domain

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

Australia

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

In Austria there are two second-level domains available for the public:

• .co.at intended for commercial enterprises
• .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 institutions and governmental bodies respectively.^[5][6]

France

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

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]

Israel

There are eight Second Level Domains:^[9]

• ac.il: Academic Institutions; administration delegated to the Inter-University Computation Center.
• co.il: Commercial Entities; administration delegated to five private registrars.
• org.il: Non-commercial Organizations; administration delegated to five private registrars.
• net.il: Israeli Internet service providers; available only to licensed providers by the Israel Internet Association.
• k12.il: Schools and Kindergartens
• gov.il: Government and Governmental System; administration delegated to ministry of finance.
• muni.il: Municipal Government
• idf.il: Israel Defense Forces; administration delegated to the army's Center of Computing and Information Systems.

Registration of other second-level domain names directly under .il is not supported.

Hebrew third level domains such as האינטרנט.org.il are available since 2010.^[10]

Russia

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 because every geographical region has its own second-level domain, such .volgograd.ru for the Volgograd Region, .irkutsk.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.^[11]

South Africa

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.^[12] The registration is handled by NOM.ZA.^[13] and is available for free.^[14]
• .school.za for primary and secondary schools.
• .net.za for network providers.^[15]

South Korea

Spain

Spanish second-level domains include .nom.es intended for personal names, .org.es for non-profit organizations and .gob.es for government agencies.^[16]

Turkey

In Turkey, domain registrations, including the registration of second-level domains is administrated by nic.tr.^[17] There 17 active second-level domains under the .tr TLD.^[18] The registration of domains is restricted to Turkish individuals and businesses, or foreign companies with a business activity in Turkey.^[19] Second-level domains include .com.tr for commercial ventures, .edu.tr for academic institutions and .name.tr for personal use.^[20]

United Kingdom

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.^[21]

Historic second-level domains

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

Australia

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.^[22]

Canada

Prior to 12 Oct 2010 there were second level domain based on province: .ab.ca — Alberta, .bc.ca — British Columbia, .mb.ca — Manitoba, .nb.ca — New Brunswick, .nf.ca — Newfoundland, .nl.ca — Newfoundland and Labrador, .ns.ca — Nova Scotia, .nt.ca — Northwest Territories, .nu.ca — Nunavut, .on.ca — Ontario, .pe.ca — Prince Edward Island, .qc.ca — Quebec, .sk.ca — Saskatchewan, .yk.ca — Yukon

Since 2010, some have been replaced (for example, alberta.ca) while others have remained under the provincial two letter SLD (e.g., transport Ontario www.mto.gov.on.ca) while others have been moved to more traditional subdomains www.transportation.alberta.ca).

France

Historic second-level domains for France included: .tm.fr (for brands), .com.fr (for commercial use) and .asso.fr. ^[23][24]

The Netherlands

Historic second-level domains for The Netherlands included: .co.nl (for commercial use) ^[25][26]

Yugoslavia

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.^[27]

Tuvalu

Historic second-level domains for Tuvalu included: co.tv

Legal issues

As a result of ICANN's generic top-level domain (gTLD) expansion,^[28] 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.^[29] 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.^[30]

See also

• Single-letter second-level domains
• Domain Name System
• Top-level domain
• Country code top-level domain
• Subdomain

References

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. "Rules for the Allocation of Domain Names Under the Israel Country Code Top Level Domain ("IL ")". Israel Internet Association - ISOC-IL. August 2010. Retrieved 10 June 2014.
10. Hebrew Domain Names
11. "Reserved domain names". Retrieved 29 October 2014.
12. "NOM.ZA NameSpace: Conditions of Registration". Retrieved 29 October 2014.
13. "2007 September 26: NOM.ZA reply to ZADNA policy". Retrieved 29 October 2014.
14. "2007 September 26: NOM.ZA reply to ZADNA policy". Retrieved 29 October 2014.
15. "Clarifying ZA SLD Policies" (PDF). Retrieved 31 October 2014. horizontal tab character in |title= at position 11 (help)
16. "Country Domain Extensions". Retrieved 31 October 2014.
17. "Overview". Retrieved 29 October 2014.
18. "Who could register which domain name?". Retrieved 29 October 2014.
19. "Can an individual or a company in abroad register a ".tr" domain name?". Retrieved 29 October 2014.
20. "Who could register which domain name?". Retrieved 29 October 2014.
21. "Second level domains". Retrieved 29 October 2014.
22. "the australian second level domain name system". Retrieved 31 October 2014.
23. "Useful information about .fr domains". Retrieved 31 October 2014.
24. "ICANN-Registrar: French Domains with Accents". Retrieved 31 October 2014.
25. "Commercial, national & international character with a .co.nl domain name". Retrieved 25 January 2016.
26. ".Co.NL WhoIS". Retrieved 25 January 2016.
27. ".RS - Republic of Serbia .ME - Republic of Montenegro (Former parts of Yugoslavia) Formerly .YU and .CS Country Codes.". Retrieved 31 October 2014.
28. "Delegated strings". Retrieved 29 October 2014.
29. 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.
30. 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.