Top-Level Domain
The domain name system allows users to refer to websites and other Internet resources using names rather than the all-numeric IP addresses assigned to each computer on the Internet. Each domain name consists of a series of character strings separated by dots. The right-most string is the top-level domain (TLD). Every TLD is managed by a single registry.
IANA currently lists the following eligible categories of TLDs:[1]
- Approved generic TLDs;
- Two-letter country codes based on the ISO 3166-1 alpha-two code (country code top level domains);
- IDN Fast Track approved strings;
- Strings eligible under ICANN Board Resolution 00.74 (currently this category applies to only one domain, .eu);[2]
- "Grandfathered" TLDs from prior to 2000, based on "exceptionally reserved" codes in the ISO 3166-1 standard (this category currently applies to two TLDs - .uk and .ac);
- Infrastructure domain (.ARPA); and
TLD Growth - Overview from 1983 to 2021[edit | edit source]
| Dates | TLDs | Use | Reason | Significance |
|---|---|---|---|---|
| 1983 | .no | country code TLD | Restricted to use by entities in Norway | The first ccTLD |
| October 1984 | .com, .net, .org | Open | Any person or entity is permitted to register a domain name using these TLDs | The first gTLDs |
| October 1984 | .edu, .gov, .mil | Limited; an entity has sponsored the operation of this TLD | For higher educational institutions, United States governmental entities and agencies, and divisions, services and agencies of the United States Department of Defense, respectively | The first gTLDs |
| 1985 | .us, .uk .il | ccTLDs | USA, UK, Israel | The second, third, and fourth ccTLDs |
| 1986 | .au, .de, .fi, .fr, .is, .kr, .nl, .se | ccTLDs | Australia, Denmark, Finland, France, Iceland, South Korea, Netherlands, Sweden | The next eight ccTLDs |
| November 3, 1988 | .int | Limited; sponsored | For organizations, offices, and programs endorsed by a treaty between two or more nations | In response to a request by NATO |
| March 1994 | Jon Postel's RFC 1591 establishes the baseline standards for eligible TLDs. | |||
| 1996 | Jon Postel drafts "New Registries and the Delegation of International Top Level Domains" | |||
| 1998 | Domain deregulation; ICANN is formed to oversee Internet names and numbers | |||
| May 2000 | .arpa | Limited; sponsored | All Internet infrastructure databases | one of the original TLDs, .arpa is re-designated at this time as an Address and Routing Parameter Area, critical to maintaining the stability of the Internet |
| November 16, 2000 | .aero, .biz, .coop, .info, .museum, .name, .pro | Sponsored gTLDs | ||
| June 29, 2006 | Test domains | per ICANN Board Resolution 07.47 | eleven such domains have been delegated thus far | |
| 2007 | .cat, .eu, .asia | Sponsored specifically for a cultural, ethnic, or regional group | Represents Catalan language and culture, the countries in the European Union, and the Asian continent, respectively | The first TLDs to denote geographical, geopolitical, ethnic, social, or cultural representation |
| October 30, 2009 | IDN ccTLD Fast Track Process is approved by the ICANN Board | |||
| .jobs, .mobi, .tel, .travel | limited to entities having something to do with the phrase comprising the TLD in question | |||
| May 5, 2010 | مصر السعودية امارات | IDN ccTLDs | From right to left, for Egypt, Saudi Arabia, and the United Arab Emirates | For the first time in the history of the Internet, non-Latin characters are being used for top-level domains |
| April 2011 | .xxx | Sponsored gTLD | ICM Registry had submitted proposals for this sTLD for pornographic sites since 2000 | |
| June 20, 2011 | ICANN Board votes to dramatically increase the number of gTLDs from the 22 already in operation | |||
| January 12, 2012 | community or standard | applicant decides if the nTLD is for a defined community consisting of a restricted population; the distinction between sponsored/unsponsored TLDs is deemed irrelevant to this round of nTLDs | The application window for All New gTLD Applications opens | |
| June 13, 2012 | -- | -- | -- | Reveal Day: 1,930 applications for new gTLDs submitted; 751 of which were contested |
| July 15, 2013 | .сайт, .онлайн, .شبكة, .游戏 | -- | -- | First four IDN nTLD aggreements signed |
| November 9, 2014 | -- | -- | -- | 400th gTLD was delegated |
| 20 May 2017 | ccTLDs | -- | -- | 255 ccTLDs delegated |
| June 2020 | IDN ccTLDs | -- | -- | 61 IDN ccTLDs approved |
| March 2021 | -- | -- | -- | IANA lists 1589 TLDs (1503 in use, 67 not assigned/revoked, 8 retired, 11 test domains) |
Varieties of TLDs[edit | edit source]
There are different types of TLDs.
gTLDs[edit | edit source]
- brand TLDs - corporations use their corporate name as their website's top-level identifier instead of .com or .biz domain space
- community TLDs relate to local events, gatherings, or organizations.
- geoTLDs represent geographical or regional areas that are not countries with three or more ASCII characters.
- hSTLDs
- nTLDs - domains that were introduced beginning in October 2013
- sTLDs - has a sponsor for a specific purpose, such as to represent a specific ethnic community, professional group, or geographical location.
ccTLDs[edit | edit source]
Country-code TLDs are delegated to a designated ccTLD registry, which is operated by a ccTLD Manager, according to local policies that are adapted to meet the economic, cultural, linguistic, and legal circumstances of the country or territory involved.
- TLDs with two ASCII characters have been established for over 250 countries and external territories.
- TLDs with non-ASCII characters designated for a country or geographic region.
Operating Mode[edit | edit source]
TLDs operate in different manners but can be categorized in some simple ways:
- Open - Operating and offering both registration and resolution services.
- Closed - Not accepting registrations, may be resolving evergreen/legacy/infrastructure subdomains.
Level of Restriction[edit | edit source]
- Unrestricted - If there are no requirements that must be met in order to register a name under a TLD, that TLD is Unrestricted.
- Restricted - Requiring Local Physical Address, Local Tax ID, or other specific criteria to qualify.
Reserved Names[edit | edit source]
- country code top-level domains
- related to ICANN
- related to IANA functions
- names of countries and territories
- names of international and intergovernmental organizations
- names that a registry operator uses to operate the gTLD