What is Classless Inter-Domain Routing

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CIDR, also referred to as supernetting, assigns IP addresses to more efficiently distribute addresses.

This replaced the previous system based on Class A, B, and C networks.

When you have a group of IP addresses, it’s called a block.

CIDR blocks share the same prefix and contain the same number of bits.

Supernetting is the combination of multiple connecting CIDR blocks into a larger whole, sharing a common network prefix.

CIDR Block Characteristics

IP addresses in blocks are continuous
First address of a block is divisible by the number of addresses of a block
Size of the block should be a power of 2

Parts of CIDR IP addresses

Benefits of CIDR

Reduces entries in the routing table
Reduce wasted IP address space