Types of Domain Name: The Top Level Domain (TLD)

Types of Domain Name: The Top Level Domain (TLD)

How it all began

The Domain Name System (DNS) was created back in the 1980s. It is administered by an American multi stakeholder group and non-profit organization called ICANN (Internet Corporation for Assigned Names and Numbers).

Back then the DNS was divided into two main groups of Top Level Domains (TLDs):

1. Country code top-level domains (ccTLD). Each was to represent a country or nation.

2. Generic top-level domains (gTLD). These were to represent various categories of names and organisations; some originally specific to the US. The first seven to be instigated were: com, org, edu, gov, and mil (in 1984), net (in 1985), and int (in 1988). Each name was intended for a specific use:

The Original Generic Top Level Domains

commercial business entities, trading companies.

not-for-profit organisations and charities.

higher educational institutions.

government agencies, federal and local.

military entities/establishments.

providers of network services. ISP’s. Portal (umbrella) sites.

international treaty-based organisations.

A special eighth name was also created at the beginning for the management of the whole DNS infrastructure. This was .arpa (originally intended to be used transitionally for the ARPANET, but subsequently used as a ‘backronym’ for Address and Routing Parameter Area).

Of the original top level domains only .com, .net and .org were open to registration by the public. Their original intended use was never rigorously enforced, and these three domain names can be registered by the public anywhere in the world and used interchangeably for just about any purpose.

In accordance with DNS networking protocols a complete domain name is made up of several parts, each separated by a period (pronounced ‘dot’). The right-most part beyond the final dot is called the top-level domain or TLD (often likened to a filename extension and sometimes referred to as ‘the domain name extension’).

The Two Types of Domain at the Top Level

The Generic Top Level Domain: gTLD

A TLD with three or more characters is known as a Generic top-level domain, or gTLD. These can be further subdivided into sponsored (sTLD) and unsponsored (uTLD) types. Some gTLDs have certain restrictions and these are known as grTLDs.

Over the years more gTLDS were created, until by 2011 there were 22 available for public registration. Then, in 2012 ICANN began allowing various organisations and companies to register and include their own gTLDs in the DNS. This saw an exponential increase in the number of gTLDs (sometimes unofficially designated as ‘new’ or nTLDs). There are now well over 1200 gTLDs available, and the list continues to grow! With so many domain extensions available, before deciding to register one, there are a lot of points worth consideration.

The Country Code Top Level Domain: ccTLD

Another form of TLD is the country code top-level domain (ccTLD). These are reserved for a country, sovereign state, or dependent territory. Unlike the three letter gTLDs, country code TLDs are identified by two letters, and with some historical exceptions, the code for any territory is the same as its two-letter ISO 3166 code. A two lettered TLD can only be a ccTLD. The first registered ccTLD was .no (Norway), which was registered in 1983, followed by .us, .uk, and .il in 1985, and then .au, .de, .fi, .fr, .is, .kr, .nl, and .se in 1986. There are now over 300 ccTLDs in use. The responsibility for operating each ccTLD is designated to national organisations, which manage and operate them according to local policies that are adapted to best meet the economic, cultural, linguistic, and legal circumstances of the country or territory involved. In the UK that organisation is Nominet.

Types of Domain - the ccTLD map
Map of ccTLD codes showing comparative registry sizes

Marketing of the ccTLD

Country code TLDs were intended to be used by organisations and citizens of the country they specified. However, some countries have found a lucrative international market for their ccTLDs if the letters concerned present the possibility of an alternative use. For example, .co is the ccTLD assigned to Colombia, it’s not a gTLD, but the Columbian authorities are more than happy to globally market it as one, i.e. as an alternative to (the depleted) .com. Another example is the domain name .tv. This is the ccTLD for Tuvalu, but its domain registry has been opened up to the world. The domain name is popular because it is an abbreviation of the word television, and that popularity has made it a very valuable economic asset indeed to this tiny, independent, South Pacific Commonwealth Island! These two examples are far from alone, and no doubt bolstered by this sort of practice, ccTLDs currently account for nearly half the total domain name industry.

Full updated alphabetical list of all TLDs in plain text format.

Administration and Policy

The right for any given entity to acquire a domain name has been delegated by ICANN to various accredited domain name registrars. The different types of domain, i.e. each TLD is administered by an individual organisation operating the relevant registry. A complete list of registries is held by ICANN. For gTLDs, information on the registrants (e.g. the registrant’s identity, name servers, expiration dates, etc.) of domain names is held in a database by ICANN, and is publicly accessible to all via the WHOIS protocol. For ccTLDs, their accredited domain registries maintain the relevant WHOIS information.

Responsibility for maintaining registration details

For all types of domain name, the registrant is responsible for maintaining accurate and up to date information for the administrative contact, technical contact, billing contact, and the DNS server records.

Administrative contact
The registrant may designate an administrative contact to manage the domain. This person usually has the highest level of control over the domain.

Technical contact
The registrant may designate a technical contact to manage the DNS name servers and other technical requirements of the domain registry.

Billing contact
The registrant may designate a billing contact who will be responsible for receiving billing invoices from the registrar and paying any applicable fees.

Note: for all types of domain a single person (or persons in combination) may fulfil the role of any or all of the legal contacts.

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