The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. It also lists mail exchange servers accepting e-mail for each domain.
In providing a worldwide keyword-based redirection service, DNS is an essential component of contemporary Internet use.
Useful for several reasons, the DNS pre-eminently makes it possible to attach easy-to-remember domain names (such as "wikipedia.org") to hard-to-remember IP addresses (such as 22.214.171.124). People take advantage of this when they recite URLs and e-mail addresses.
In a subsidiary function, the domain name system makes it possible for people to assign authoritative names without needing to communicate with a central registrar each time.
For the rest of the Wikipedia entry on the above term, go here.
Domain Naming Prefix: Is the default domain name used when only the hostname is given. In order for Dynamic Domain Naming Server (DDNS) to work correctly, you must have the prefix preconfigured. By default, the prefix is not set.