Huawei Certified Network Professional – Routing and Switching (HCNP-RS, legacy) — Question 9

Which of the following subnet masks can be used to divide a Class C network into 5 subnets, with each subnet containing a maximum of 20 hosts?

Answer options

• A. 255.255.255.192
• B. 255.255.255.240
• C. 255.255.255.224
• D. 255.255.255.248

Correct answer: C

Explanation

The correct answer is C (255.255.255.224) because it allows for 8 subnets, each with 30 usable hosts, which meets the requirement of 5 subnets for 20 hosts each. Option A (255.255.255.192) provides 4 subnets with 62 hosts, which is insufficient. Option B (255.255.255.240) yields 16 subnets but only 14 hosts per subnet, which does not satisfy the requirement. Option D (255.255.255.248) offers 32 subnets, but only 6 hosts each, making it unsuitable as well.