The following lines were added (+) and removed (-):
Before CIDR IP networking was classful. In 1981 three different sizes of networks were defined. Basically, due to an IP address shortage, the classful system was eventually replaced by a new system that is known as C.I.D.R. (Classless Inter-Domain Routing).Before CIDR nearly all IP networking was considered classful. In 1981 three different sizes of networks were defined. Basically, due to an IP address shortage, the classful system was eventually replaced by a new system that is known as C.I.D.R. (Classless Inter-Domain Routing).