Given a network that requires at most 60 usable hosts per subnet, which CIDR notation provides the smallest subnet mask?

Given a network that requires at most 60 usable hosts per subnet, which CIDR notation provides the smallest subnet mask?

• A. /27
• B. /26
• C. /24
• D. /25

Answer: (B)

Understanding how many usable hosts a subnet can support is determined by the number of host bits. Usable hosts per subnet = 2^n - 2, where n is the number of host bits. To accommodate up to 60 usable hosts, you need 2^n - 2 ≥ 60, so 2^n ≥ 62. The smallest n that works is 6, which corresponds to a /26 subnet (64 total addresses, 62 usable). A /27 would provide only 30 usable hosts, which is not enough. A /25 or /24 would provide more hosts than needed, so they aren’t the smallest solution. Therefore, the smallest suitable CIDR is /26.

Understanding how many usable hosts a subnet can support is determined by the number of host bits. Usable hosts per subnet = 2^n - 2, where n is the number of host bits.

To accommodate up to 60 usable hosts, you need 2^n - 2 ≥ 60, so 2^n ≥ 62. The smallest n that works is 6, which corresponds to a /26 subnet (64 total addresses, 62 usable).

A /27 would provide only 30 usable hosts, which is not enough. A /25 or /24 would provide more hosts than needed, so they aren’t the smallest solution. Therefore, the smallest suitable CIDR is /26.