What is an IP address?

Published 06/08/2004 16:07   |    Updated 13/02/2009 13:09
What is an IP address?

An IP address is a unique number that devices implementing the Internet Protocol (IP) use in order to identify each other on a network. Any participating device—including routers, computers, time-servers, FAX machines, and some telephones—must have its own address. This allows information passed onwards on behalf of the sender to indicate where to send it next, and for the receiver of the information to know that it is the intended destination.


The numbers used in IP addresses range from to, though some of these values are reserved for specific purposes. This does not provide enough possibilities for every internet device to have its own permanent number, and the Dynamic Host Configuration Protocol (DHCP) gives clients dynamic IP addresses that are recycled when they are no longer in use. Systems such as network printers, web servers and email servers are permanently connected to the internet—so they are generally allocated static IP addresses which consistently identify the machine every time it is online.


IP addresses are conceptually similar to phone numbers, except used in LANs (Local Area Network), WANs (Wide Area Network), and the Internet. Because the numbers are not easy for humans to remember, the Domain Name System provides a service analogous to an address book. Several servers on the internet are dedicated to performing the translation from a name into an address, and this process of conversion is known as resolution of the domain name.




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