Black and white Computer

For routers to be able to determine the correct route between two computers, each computer needs to have an address so that the routers know where to send the data. In networking terms, an address is a unique identifier for a given device. Even routers themselves have addresses – in fact, for any destination address (like a Web server), routers only need to know the address of the next nearest router to the destination, and they simply hand over responsibility for delivering the data to that router. Eventually the last router in the chain knows the Web server itself and can deliver the data to it. On the Internet, an Internet Protocol (IP) address is a four-byte number, usually written in ‘dotted decimal’ notation; for example 10.43.172.77. Every device in the world that connects directly to the Internet has a unique four-byte IP address. This means that there are over four billion possible IP addresses (although around 20 million addresses are reserved for special uses). This may se...