Second-Level Domain Names

The second-level domain is the segment of the domain name that is located on the left of the final dot. In other words, it is located to the left of the top-level domain.

General Second-Level Domains

In many cases, the second-level domain is the part that you register. For example, in the domain example.com, "example" is the second-level domain.

Country Code Second-Level Domains (ccSLD)

Some countries restrict the second-level domain. These countries require that the second-level domain is one of several pre-determined second-level domains. For these countries, you are not permitted to register domain names under the top-level domain. It must be registered under a second-level domain.

For example, mydomain.uk is not permitted but mydomain.co.uk is permitted.

ccSLD Usage

Country code second-level domains have a pre-defined purpose. When you register a domain name, you need to choose the second-level domain that best corresponds to your type of activity. For example, you can only use the .org.uk domain if you are a non-profit organization.

Here's a list of ccSLDs used in the UK:

  • .ac.uk - academic (tertiary education and research establishments) and learned societies.
  • .co.uk - commercial/general
  • .gov.uk - government (central and local)
  • .ltd.uk - limited companies
  • .me.uk - personal
  • .mod.uk - Ministry of Defence and HM Forces public sites
  • .net.uk - ISPs and network companies
  • .nic.uk - network use only
  • .nhs.uk - National Health Service institutions
  • .org.uk - non-profit organizations
  • .plc.uk - public limited companies
  • .police.uk - police forces
  • .sch.uk - local education authorities, schools, primary and secondary education, community education

ccSLDs - Exceptions

In some countries, various domain names were created before the ccSLD restriction was implemented. Therefore, it is possible to find examples of domain names that breach the ccSLD rule.

UK examples include parliament.uk (Parliament), bl.uk and british-library.uk (the British Library), nls.uk (the National Library of Scotland), nhs.uk (The National Health Service), and jet.uk (UKAEA as operator of the Joint European Torus experimental fusion tokamak).

Reserved Second-Level Domains

There are currently three (non country specific) second-level domains reserved by the Internet Assigned Numbers Authority (IANA). These domains are:

  • example.com
  • example.net
  • example.org

More about these here.

Registering Your Domain Name

You register your domain name through an ICANN-accredited domain name registrar (or partner site) like ZappyHost.

To register your domain name, enter your preferred domain into the search form. If it's available, simply proceed to the checkout. ZappyHost will walk you through the registration step by step.