Ip global positioning blog

CIDR, short for Classless Inter-Domain Routing is a prefix-based format for IP addresses. We was used to see IP addresses like 4 numbers separated by periods and they are called IPv4 addresses, but the internet is prospering quickly, we can connect to the internet from our personal computers, from portable computers, from pda’s, and from mobile phones. Think what will happen when each mobile phone will have a permanent connection to the internet. How many mobile phones are in the world ? And that isn’t everything, in short time almost every device will have a connection to the internet. A CIDR IP address consist of a IPv4 address followed by a slash and a number from 0 to 32. This number is the prefix length, the number of shared initial bits. The IPv4 address is 32 bit long, so, if a CIDR address is followed by number 16, this means that the first 16 bits from the IP are shared, in other words, 256 class C, equivalent to 1 class B. A CIDR address with 24 in the end is equivalent to 1 class C, or 256 hosts. In this way the internet will never run out of IP addresses.