The Classless Inter-domain Routing (CIDR) notation (pronounced cider) is a compact method for specifying IP addresses and their routing suffixes. This notation gained popularity due to its granularity when compared with classful addressing because it allows subnet masks of variable length.
The CIDR notation is specified by an IP address and network suffix. The network or IP suffix represent the number of network bits. IPv4 addresses are 32 bit, so the network can be between 0 and 32. The most common suffixes are /8, /16, /24, and /32.
To visualize it, take a look at the following CIDR-to-Netmask conversion table:
|
CIDR |
Netmask |
|
/8 |
255.0.0.0 |
|
/16 |
255.255.0.0 |
|
/24 |
255.255.255.0 |
|
/32 |
255.255.255.255 |
