Because IP addresses are difficult to remember in their dotted-decimal notation,
a naming convention called domain names was established that’s more
natural for people to use. Domain names such as www.cisco.com are registered
and associated with a particular public IP address. The Domain Name
System (DNS) maps a readable name to an IP address. For example, when you
enter http://www.cisco.com into a browser, the PC uses the DNS protocol to
contact a DNS name server. The name server translates the name
http://www.cisco.com into the actual IP address for that host..