200-901 Network Fundamentals Practice Question
A network engineer is subnetting the network 192.168.1.0/24 into subnets that each support at least 50 hosts. What subnet mask should be used?
⚠ Common exam trap
Cisco often tests the distinction between the number of host bits needed versus the number of subnet bits, and the trap here is that candidates may choose /25 because it supports more hosts, overlooking that /26 is the minimum mask that meets the 50-host requirement and is the correct answer per the question's wording.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
255.255.255.192 (/26)
To support at least 50 hosts, you need 6 host bits (2^6 - 2 = 62 usable addresses). A /26 subnet mask (255.255.255.192) provides exactly 6 host bits, meeting the requirement. The original /24 network is borrowed with 2 subnet bits, yielding 4 subnets of 64 addresses each.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
255.255.255.192 (/26)
Why this is correct
A /26 mask leaves six host bits, giving 62 usable addresses, which satisfies the minimum of 50 hosts per subnet. A /27 would provide only 30 usable addresses, so 255.255.255.192 is the smallest mask that meets the requirement.
- ✗
255.255.255.224 (/27)
Why it's wrong here
A /27 mask provides only 30 usable hosts, falling short of the 50-host requirement, so hosts would be lost. It is tempting because /27 is a common subnetting choice for small departmental segments, and would be correct where each subnet must support at most 30 devices.
- ✗
255.255.255.240 (/28)
Why it's wrong here
A /28 mask yields 16 addresses, only 14 usable hosts, short of the 50 required. It is tempting because /28 is a common subnetting answer, and it would be correct if each subnet needed to support at most 14 hosts, where /26 (255.255.255.192) would instead satisfy 50 hosts.
- ✗
255.255.255.128 (/25)
Why it's wrong here
A /25 mask yields 126 usable hosts per subnet, exceeding the 50-host minimum but halving the address space into only two subnets, wasting capacity. It is tempting because it satisfies the host count, and would be correct where exactly two large subnets are needed rather than efficient allocation across the /24.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-901 exam.