N10-005 · Question #865
Which of the following subnet masks indicate a subnet with exactly 254 assignable IP addresses?
The correct answer is C. 255.255.255.0. The subnet mask 255.255.255.0 (CIDR /24) creates a block of 256 addresses. Subtracting the network address (e.g., .0) and the broadcast address (e.g., .255) leaves 254 usable host addresses - exactly what the question asks for. By comparison: 255.0.0.0 (/8) yields ~16 million…
Question
Which of the following subnet masks indicate a subnet with exactly 254 assignable IP addresses?
Options
- A255.0.0.0
- B255.255.0.0
- C255.255.255.0
- D255.255.255.254
How the community answered
(68 responses)- A6% (4)
- B1% (1)
- C90% (61)
- D3% (2)
Explanation
The subnet mask 255.255.255.0 (CIDR /24) creates a block of 256 addresses. Subtracting the network address (e.g., .0) and the broadcast address (e.g., .255) leaves 254 usable host addresses - exactly what the question asks for. By comparison: 255.0.0.0 (/8) yields ~16 million hosts, 255.255.0.0 (/16) yields ~65,000 hosts, and 255.255.255.254 (/31) is a point-to-point mask with 2 addresses and 0 usable hosts under traditional rules.
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