Classless Inter-Domain Routing notation

A compact representation of an IP address and its subnet mask using a slash and a decimal number to indicate how many leading 1 bits are in the network mask, with the remaining bits being the network host identifiers (e.g., 192.168.220.16/24). The subnet mask of 255.255.255.0 (24 mask bits) is represented as /24 in CIDR notation. CIDR replaces the class designations (A, B, and C) for IP address ranges.