With a new network being connected to the Internet every 30 minutes the Internet was faced with two critical problems * Running out of IP v4 addresses * Running out of capacity in the global routing tables In the original IP addressing scheme, we have Class A,B, C that has /8, /16, /24. Let’s say I need 10 IPs so I have to go for /24 which means I’m going to waste 154 IPs. Classless Inter-Domain Routing (CIDR) is a replacement for the old process of assigning Class A, B and C addresses with a generalized network "prefix". Instead of being limited to network identifiers (or "prefixes") of 8, 16 or 24 bits, CIDR currently uses prefixes anywhere from 13 to 27 bits. CIDR is a new addressing scheme for the Internet which allows for more efficient allocation of IP addresses than the old Class A, B, and C address scheme. (/8, /16, /24)