<Li> n indicates a bit used for the network ID . </Li> <Li> H indicates a bit used for the host ID . </Li> <Li> X indicates a bit without a specified purpose . </Li> <P> The first architecture change extended the addressing capability in the Internet, but did not prevent IP address exhaustion . The problem was that many sites needed larger address blocks than a Class C network provided, and therefore they received a Class B block, which was in most cases much larger than required . In the rapid growth of the Internet, the pool of unassigned Class B addresses (2, or about 16,000) was rapidly being depleted . Classful networking was replaced by Classless Inter-Domain Routing (CIDR), starting in 1993 with the specification of RFC 1518 and RFC 1519, to attempt to solve this problem . </P>

What are different special address in classful addressing