CyberCertPrepNetwork FundamentalsIP Addressing & SubnettingEASYFree question
What is the IPv4 'Class A, B, C' classful addressing system, and what were the historical subnet masks for each class?
- A.Classful addressing (pre-CIDR): Class A = first bit 0, range 1.0.0.0-126.0.0.0, default mask /8 (255.0.0.0), 16 million hosts per network; Class B = first bits 10, range 128.0.0.0-191.255.0.0, default mask /16 (255.255.0.0), 65534 hosts; Class C = first bits 110, range 192.0.0.0-223.255.255.0, default mask /24 (255.255.255.0), 254 hosts. CIDR (1993) replaced classful addressing with variable-length masks.
- B.Class A = /16, Class B = /24, Class C = /32.
- C.Class A = ranges 10.x.x.x (private only), Class B = 172.16-31.x.x, Class C = 192.168.x.x.
- D.Classful addressing is still used today; CIDR notation is only used in documentation.
Why A is correct