What is a domain name prefix?

Updated: March 30, 2011

Applies To: Windows Home Server 2011

A domain name consists of hierarchical labels.

The top-level domain extension is the right-most label in the domain name. For example, in www.contoso.com, com is the top-level domain name extension.

The second-level domain name is the label next to the top-level domain name extension. The second-level domain name is often created based on company name, products, or services. For example, in www.contoso.com, contoso is the second-level domain name was chosen for the company name Contoso Pharmaceuticals. The second-level domain is sometimes referred to as the hostname, which has an IP address associated with it.

The domain name prefix identifies a subdomain. The subdomain name can be used to identify services, devices, or regions. For example, Contoso Pharmaceuticals wants to allow remote users to log into the Remote Access Web Site, but does not want the Web site to be available to the public, so they create a subdomain that allows only users with appropriate permissions to access the Web site. Contoso Pharmaceuticals sets up remote.contoso.com as the subdomain, and remote is the domain name prefix.