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N10-009 · Question #478
N10-009 Question #478: Real Exam Question with Answer & Explanation
The correct answer is D: 255.255.255.240. The subnet mask 255.255.255.240 corresponds to a /28 subnet. A /28 provides 16 total IP addresses, of which 14 are usable (excluding the network and broadcast addresses). Since the requirement is 13 usable IPs, this mask fits perfectly.
Submitted by femi9· Mar 6, 2026Network implementation
Question
A network administrator is configuring a subnet that needs to support 13 usable IP addresses. Which of the following subnet masks best meets this requirement?
Options
- A255.255.255.128
- B255.255.256.192
- C255.285.256.224
- D255.255.255.240
Explanation
The subnet mask 255.255.255.240 corresponds to a /28 subnet. A /28 provides 16 total IP addresses, of which 14 are usable (excluding the network and broadcast addresses). Since the requirement is 13 usable IPs, this mask fits perfectly.
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