Final answer:
Class-based IPv4 addressing was done by dividing the available IP addresses into classes A, B, and C, with each class having a different range of addresses. The classes had different numbers of network and host bits, allowing for a varying number of networks and hosts per network. However, class-based addressing was inefficient and led to the introduction of CIDR.
Step-by-step explanation:
Class-based IPv4 addressing was done by dividing the available IP addresses into classes based on the number of network bits. The classes, A, B, and C, had different ranges of addresses allocated to them. Class A had a large number of network bits and a smaller number of host bits, allowing for a large number of hosts but a limited number of networks. Class B had a balance between the number of network and host bits, while Class C had a larger number of network bits and a smaller number of host bits, allowing for a larger number of networks but a limited number of hosts.
For example, in Class A, the first octet of an IP address was used for the network identifier, and the remaining three octets were used for host identification. This allowed for a maximum of 128 networks and 16,777,216 hosts per network. In Class B, the first two octets were used for the network identifier, allowing for a maximum of 16,384 networks and 65,536 hosts per network. In Class C, the first three octets were used for the network identifier, allowing for a maximum of 2,097,152 networks and 256 hosts per network.
However, class-based addressing led to the inefficient allocation of IP addresses, with many addresses being wasted. This led to the introduction of Classless Inter-Domain Routing (CIDR), which allows for more flexible allocation of IP addresses.