A Basic Introduction to a Range of Internet Related Concepts and Terms

What is a Domain?

Domains can be thought of as addressing elements within the DNS hierarchical structure on the Internet. These domains are identified by 'simple names' rather than by numbers eg com; org; net.

The addressing structure for domain names (eg www.abdn.ac.uk; www.allans.org) to address individual websites involves a naming convention consisting of 'simple names' separated by dots. Each 'simple name' is a sub-domain. For example:

name3.name2.name1. (eg abdn.ac.uk) where name3, name2 and name1 are all sub-domains.

'name1' is at the highest level. Often it is referred to as a top level domain (TLD ) and in its three letter or non country specific form it includes sub-domain names such as com (commercial), net (network), org (organisation - non business), edu (education institution), gov (government). These three letter domain names are sometimes referred to as Generic Top Level Domains (gTLDs).

Although it is usually possible for an organisation or individual anywhere in the world to register a domain name under some of these three character top-level domains (com, net or org) the vast majority of such registrations are in the USA. The top-level domains represented by two character country codes are perhaps more commonly used in most other countries although there is a prestige factor associated with the three character domains which tends to influence registrations and use. Examples of the two character country codes include: uk (United Kingdom); au (Australia); nz (New Zealand); fr (France); dk (Denmark).

The majority of country top level domains are sub-divided into organisational sub-domains such as ac.uk (academic in UK); com.au (Australian commercial); co.uk (UK commercial) and so on.

Recently further TLD names have been added to the existing portfolio . These include .info, .name, .biz, .museum, .coop, and .aero. Others are still under discussion including .pro.

Each TLD normally has a Domain Authority which manages the registrations of domain names to applicants. For example InterNic is the Domain Authority for .com and Nominet is the Domain Authority for .uk.

Independent companies which specialise in the sale of domain names and the hosting of websites will normally manage the actual sale of the domain names. To purchase a domain name an individual will thus normally contact a vendor (online usually) to buy a domain name of his/her choice. The vendor will then register that domain name purchase with the appropriate Domain Authority. The domain name purchased will probably consist of a TLD component plus a second level domain component (SLD) eg allans.org where allans is the SLD and org is the TLD.

To manage the domain names registered around the world and to enable addressing for the communication between systems to take place a collection of inter-communicating nameservers (computers) implement the DNS system. For each domain there is a primary nameserver which 'feeds' secondary nameservers with information about Internet entities within that domain. The process is thus one of gradually populating nameservers around the world with enough information to enable new domain names to be addressed and used. For worldwide recognition of a new domain name a period of a few days may be required.