What is IPv4?

Internet Protocol version four, or IPv4, is a system of addresses used to identify devices on a network. Originally described in 1981 in RFC791, IPv4 is the most widely used Internet layer protocol, and at this point is used by the vast majority of users to connect to the Internet.

IPv4 addresses are actually 32-bit numbers. This means that there are 232, or just over four billion, possible addresses. Over time, however, it has become clear that more addresses than this will be required to ensure ongoing growth of the Internet. The unused pool of IPv4 addresses is predicted run out in the next two years, so an alternative is required.

IPv4 counter


This gadget has been developed by Takashi Arano’s Intec NetCore. Details at http://entne.jp/tool/toollist/000101.php