Historically, what were the default subnet masks for IPv4 Class A, B, and C networks?

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Multiple Choice

Historically, what were the default subnet masks for IPv4 Class A, B, and C networks?

Explanation:
In IPv4 history, the way an address was divided into network and host parts depended on its class. The class determined how many bits were reserved for the network by default. For Class A, 8 bits are used for the network, so the default subnet mask is 255.0.0.0 (a /8), leaving 24 bits for hosts. For Class B, 16 bits are used for the network, giving 255.255.0.0 (a /16) and 16 bits for hosts. For Class C, 24 bits are used for the network, yielding 255.255.255.0 (a /24) with 8 bits for hosts. This arrangement is why those masks are historically correct: they reflect the intended balance of network versus host addresses for each class. Today we use CIDR, but these defaults show how classful addressing split address space.

In IPv4 history, the way an address was divided into network and host parts depended on its class. The class determined how many bits were reserved for the network by default. For Class A, 8 bits are used for the network, so the default subnet mask is 255.0.0.0 (a /8), leaving 24 bits for hosts. For Class B, 16 bits are used for the network, giving 255.255.0.0 (a /16) and 16 bits for hosts. For Class C, 24 bits are used for the network, yielding 255.255.255.0 (a /24) with 8 bits for hosts. This arrangement is why those masks are historically correct: they reflect the intended balance of network versus host addresses for each class. Today we use CIDR, but these defaults show how classful addressing split address space.

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