Understanding CIDR & Subnets
CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and IP
routing. It replaces the old "Class A, B, C" system with a more flexible "slash" notation (e.g.,
/24).
Common CIDR Blocks
- /32: 1 IP address. Used for specific host rules in firewalls.
- /24: 256 IPs (254 usable). Standard specific subnet (e.g., 192.168.1.x).
- /16: 65,536 IPs. Often used as the main block for a VPC in AWS/Azure.
- /8: 16 million IPs. Massive corporate networks (e.g., 10.x.x.x).
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