CIDR Range 
An IPv4 CIDR range identifies an IPv4 network (i.e. collection of IPv4 addresses). A CIDR range consists of an IPv4 address and a suffix indicating how many bits of the address make up the network mask. The suffix can be from 0 to 32 bits. 

Format:
A CIDR range is written as:
[IPv4 Address]/[prefix bit count] 

Examples:
192.168.0.1/22 
128.148.128.40/32
168.0.0.0/0
10.61.128.218/27