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 . Some TLDs now break the traditional rule that a TLD is the right most node in a URL. A TLD can have multiple nodes, like . 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. Austria. In Austria there are two second-level domains available for the public: The second-level domain France. In France, there are various second-level domains available for certain sectors, including  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. Ukraine. Ukraine second-level domains include: There are also numerous geographic names. 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: 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 "." The Netherlands. Historic second-level domains for the Netherlands included: ."co.nl" (for commercial use) Yugoslavia. In 2006 the ccTLD was replaced by ' (for Serbia) and ' (for Montenegro). Second-level domains under included: ' – for academic institutions, ' for commercial enterprises; ' for organizations and ' for residents of Montenegro. Only legal entities were allowed to register names under " 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 ' or ' is not allowed; however, the registration of sites such as ' or ' is not controlled. Experts say that further restrictions are needed for second-level domains under the new gTLD ', as well. For example, second-level domains under ' or " can be easily misused by companies and therefore are a potential threat to Internet users. Second