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.
Contents
- Australia
- Austria
- Brazil
- France
- Hungary
- New Zealand
- Israel
- Russia
- South Africa
- Spain
- Turkey
- United Kingdom
- United States
- Historic second level domains
- Canada
- The Netherlands
- Yugoslavia
- Tuvalu
- Legal issues
- References
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.
Australia
In Australia, currently there are 16 active second-level domains, all managed by auDA.
Open second-level domains (available for the public):
Closed second-level domains (restricted to certain sectors):
Community Geographic Domain Names (restricted to certain geographic regions for community use):
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.
Austria
In Austria there are two second-level domains available for the public:
The second-level domain
Brazil
There are at least 66 second level domains:
France
In France, there are various second-level domains available for certain sectors, including
Hungary
There are 21 active second-level domains in Hungary, including:
The registration of second-level domains is managed by the Council of Hungarian internet providers.
New Zealand
Open second-level domains (available for the public):
Closed second-level domains (restricted to certain sectors):
Israel
There are eight Second Level Domains:
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.
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.
South Africa
Under the .za ccTLD there are several second-level domains in use. These include:
Spain
Spanish second-level domains include .nom.es intended for personal names, .org.es for non-profit organizations and .gob.es for government agencies,com.es for companies.
Turkey
In Turkey, domain registrations, including the registration of second-level domains is administrated by nic.tr. There 17 active second-level domains under the .tr TLD. The registration of domains is restricted to Turkish individuals and businesses, or foreign companies with a business activity in Turkey. Second-level domains include .com.tr for commercial ventures, .edu.tr for academic institutions and .name.tr for personal use.
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.
United States
A two-letter second-level domain is formally reserved for each U.S. state, federal territory, and the District of Columbia:
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.
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.
The Netherlands
Historic second-level domains for The Netherlands included: .co.nl (for commercial use)
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.
Tuvalu
Historic second-level domains for Tuvalu included: co.tv
Legal issues
As a result of ICANN's generic top-level domain (gTLD) expansion, 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. 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.