How many addresses are spanned by the CIDR address 214.13.192.0/21, and what range do they span? Solution Classless inter domain routing (CIDR) is a method to assign addresses outside the standard Class A, B, and C structure that is used by IPv6. Specifying the number of bits in the subnet mask A CIDR IP address looks like a normal IP address, it ends with a slash followed by a number, it is called as IP network prefix. it reduce the size of routing tables and make more IP addresses available within organizations. Start IP address: 214.13.192.0 End IP address: 214.13.199.255 Total Addresses(number of hosts): 2,048 IP address class : 8 Class C.