CIDR

Proper noun

 * 1)  normally an IP address notation such as 192.168.1.0/24 indicating a block of addresses. The number after the slash indicates how many bits are in the mask; bits to the right are not masked.
 * 192.168.1.35 and 192.168.1.252 are both valid addresses in the CIDR block 192.168.1.0/24, but 192.168.2.35 is not.