CIDRmerkintöjä

CIDRmerkintöjä, or CIDR notation, is a method for representing IP addresses and their associated routing prefixes. It was developed by the Internet Engineering Task Force (IETF) to provide a more flexible and efficient way to allocate IP addresses compared to the older classful addressing system. CIDR notation combines an IP address with a prefix length, which indicates how many bits in the address are used for the network portion.

The format of CIDR notation is an IP address followed by a forward slash and the prefix length. For example, 192.168.1.0/24 represents an IP address range where the first 24 bits define the network. This means that the first three octets (192.168.1) are fixed for the network, and the last octet can vary, allowing for 256 possible IP addresses within that network. A shorter prefix length, like /16, indicates a larger network with more available IP addresses, while a longer prefix length, like /27, signifies a smaller network.

CIDR is crucial for efficient routing on the internet. By allowing for variable-length subnet masks, network administrators can create more granular networks, reducing the size of routing tables and improving the overall performance of the internet. This aggregation of IP addresses into larger blocks, known as supernets, is a fundamental concept in modern IP addressing and routing.