When a visitor types your domain name into an Internet browser, it is sent to one of several servers on the Internet that store a master list of domain names. This server converts the name into its assigned IP address (e.g., 123.123.123.123), a number that functions exactly like a phone number - except that the customer's "call" is routed through a network of switches and fiber-optic cables optimized for data transfer. The master list server sends the request to a "Domain Name Server" (DNS) responsible for handling calls to this address. For example, a Web host's Domain Name Server stores the addresses of all the sites located at the host's facility (which could number in the thousands). When the host's DNS receives a call to an address it recognizes, it sends a positive acknowledgement to the master list server and, in turn, directs the call to the server that stores the Website.