What is CIDR Notation?
CIDR (Classless Inter-Domain Routing) notation is a compact way to specify IP addresses and their associated routing prefix. For example, 192.168.1.0/24 means the first 24 bits are the network address, leaving 8 bits for host addresses (254 usable hosts).
Common CIDR Blocks
| CIDR | Subnet Mask | Hosts | Use Case |
|---|---|---|---|
| /32 | 255.255.255.255 | 1 | Single host |
| /28 | 255.255.255.240 | 14 | Small LAN |
| /24 | 255.255.255.0 | 254 | Standard LAN |
| /16 | 255.255.0.0 | 65,534 | Campus network |
| /8 | 255.0.0.0 | 16,777,214 | Large ISP |