Classful vs. Classless Addressing: What’s the Difference?
Classful and classless addressing describe two different ways to structure an IPv4 address. Classful addressing came first, in the early internet of the 1980s. It used fixed Class A, B, and C ranges. That rigid structure eventually led to serious IPv4 address exhaustion. CIDR arrived in 1993 and introduced classless addressing instead, allowing flexible prefixes...
