What is CIDR?
A method for allocating IP addresses and routing that replaces the old classful system.
Detailed Explanation
CIDR notation uses a suffix (like /24) to indicate how many bits are used for the network portion of an address. This allows for flexible network sizing without being restricted to Class A, B, or C boundaries. For example, 192.168.1.0/24 means the first 24 bits are the network portion, leaving 8 bits (256 addresses) for hosts. CIDR has greatly improved IP address allocation efficiency.
Examples
- •10.0.0.0/8 - 16,777,216 addresses
- •172.16.0.0/12 - 1,048,576 addresses
- •192.168.1.0/24 - 256 addresses