CIDRnotatsioonis

CIDRnotatsioonis, or Classless Inter-Domain Routing notation, is a method for allocating IP addresses and routing Internet Protocol packets. It was introduced in 1993 by Paul Mockapetris and David Mills to replace the older classful addressing system. The primary advantage of CIDR is its ability to reduce the size of routing tables and conserve the limited supply of IPv4 addresses.

In CIDR notation, an IP address is represented by its network address followed by a slash and a number. This number, known as the prefix length, indicates the number of bits in the IP address that represent the network portion. For example, 192.168.1.0/24 signifies an IP address where the first 24 bits (the first three octets) define the network, and the remaining 8 bits define the host within that network. This contrasts with the older classful system, which used fixed boundaries for network and host portions based on address classes (A, B, C).

CIDR allows for the creation of variable-length subnet masks (VLSMs). This means that network administrators can divide larger blocks of IP addresses into smaller, more manageable subnets of varying sizes, optimizing address allocation and network efficiency. This flexibility is crucial for efficient IP address management and effective routing on the internet. CIDR notation is fundamental to how the internet's routing infrastructure operates.