second-level domain

In the Domain Name System (DNS) hierarchy, a second-level domain (SLD or 2LD) is a domain that is directly below a top-level domain (TLD). For example, in , is the second-level domain of the 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 ccSLD, while companies would register under . Strictly speaking, domains like .ac.uk and .co.uk are second level domain themselves, since they are right below a TLD. A list of the official TLDs can be found at icann.org and iana.org. An ordinal-free term to denote domains under which people can register their own domain name is public suffix domain (PSD).

Country-code second-level domains

Algeria

Australia

Austria

In Austria there are two second-level domains available for the public:
*.co.at intended for commercial enterprises
*.or.at intended for organizations.
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.

Brazil

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.

Hungary

New Zealand

Pakistan

India

Israel

Japan

Russia

South Africa

South Korea

Spain

Sri Lanka

Thailand

Trinidad and Tobago

* co.tt
* com.tt
* org.tt
* net.tt

* travel.tt
* museum.tt
* aero.tt
* tel.tt
* name.tt
* charity.tt
* mil.tt
* edu.tt
* gov.tt

Turkey

In Turkey, domain registrations, including the registration of second-level domains is administrated b
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.

Ukraine

Ukraine second-level domains include:
*.gov.ua – available for government agencies.
*.com.ua – for commercial use.
*.in.ua – for commercial use.
*.org.ua – intended for non-profit organizations.
*.net.ua – intended for Internet providers.
*.edu.ua – for academic institutions.

There are also numerous geographic names.

United Kingdom

United States

A two-letter second-level domain is formally reserved for each U.S. state, federal territory, and the District of Columbia.

Zambia

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: originally intended for conferences; for the Australian Academic and Research networks; ' for general information, ' and ' 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., Calgary Board of Education www.cbe.ab.ca) and others were 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 ''{{Not a typo, .asso.fr.''

The Netherlands

Historic second-level domains for the Netherlands included:
.''co.nl'' (for commercial use)

Yugoslavia

In 2006 the {{Not a typo, .yu ccTLD was replaced by ''{{Not a typo, .rs'' (for Serbia) and ''{{Not a typo, .me'' (for Montenegro).
Second-level domains under {{Not a typo, .yu included:
''{{Not a typo, .ac.yu'' – for academic institutions, ''{{Not a typo, .co.yu'' for commercial enterprises; ''{{Not a typo, .org.yu'' for organizations and ''{{Not a typo, .cg.yu'' for residents of Montenegro.
Only legal entities were allowed to register names under ''{{Not a typo, .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 ''{{Not a typo, .olympics'' or ''{{Not a typo, .redcross'' is not allowed; however, the registration of sites such as ''{{Not a typo, olympics.example'' or ''{{Not a typo, redcross.example'' is not controlled.
Experts say {{who, date=May 2021 that further restrictions are needed for second-level domains under the new gTLD ''{{Not a typo, .health'', as well. For example, second-level domains under ''{{Not a typo, .tobacco.health'' or ''{{Not a typo, .diet.health'' can be easily misused by companies and therefore are a potential threat to Internet users.{{cite journal, last1=Mackey, first1=TK, last2=Liang, first2=BA, last3=Kohler, first3=JC, last4=Attaran, first4=A, title=Health Domains for Sale: The Need for Global Health Internet Governance, journal=J Med Internet Res, date=5 March 2014, volume=16, issue=3, doi=10.2196/jmir.3276, pmid=24598602, url=http://www.jmir.org/2014/3/e62/, access-date=2014-10-29, pmc=3961808, page=e62

See also

*Single-letter second-level domains
*Domain Name System
*Top-level domain
*Country code top-level domain
* Subdomain
*Private sub-domain registry
*Public Suffix List
*.ac (second-level domain)
*.edu (second-level domain)

References

{{Reflist

{{course assignment , course = Education Program:University College London/MSIN1003 Information World (Autumn 2014) , term = 2014 Q3

{{DEFAULTSORT:Second-Level Domain
Domain Name System