This 200-901 practice question tests your understanding of network fundamentals. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network administrator needs to assign IP addresses to 50 hosts in a subnet. Which subnet mask provides the minimum required number of usable addresses while minimizing waste?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
255.255.255.192 (/26)
62 usable, sufficient and minimal waste.
255.255.255.224 (/27)
Why wrong: 30 usable, not enough.
255.255.255.240 (/28)
Why wrong: 14 usable, not enough.
255.255.255.128 (/25)
Why wrong: 126 usable, wastes addresses.
Answer choices
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)
A /26 subnet mask (255.255.255.192) provides 64 total addresses per subnet, of which 62 are usable (2^6 - 2 = 62). This is the smallest power-of-two block that can accommodate 50 hosts, minimizing waste while meeting the requirement.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
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
62 usable, sufficient and minimal waste.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
255.255.255.224 (/27)
Why it's wrong here
30 usable, not enough.
255.255.255.240 (/28)
Why it's wrong here
14 usable, not enough.
255.255.255.128 (/25)
Why it's wrong here
126 usable, wastes addresses.
Common exam traps
Cisco often tests the distinction between 'total addresses' and 'usable addresses' — candidates mistakenly count the total 64 addresses as usable, forgetting to subtract the network and broadcast addresses, or they choose a mask that provides exactly 50 total addresses (which is impossible since host bits must be a power of 2).
Detailed technical explanation
The subnet mask determines the number of host bits: /26 leaves 6 host bits, yielding 2^6 = 64 total addresses, minus 2 for the network and broadcast addresses. In real-world network design, administrators often use Variable Length Subnet Masking (VLSM) to allocate subnets of different sizes; for 50 hosts, a /26 is the optimal choice because the next smaller mask (/27) cannot support the required hosts, and the next larger (/25) wastes over half the address space.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: 255.255.255.192 (/26) — A /26 subnet mask (255.255.255.192) provides 64 total addresses per subnet, of which 62 are usable (2^6 - 2 = 62). This is the smallest power-of-two block that can accommodate 50 hosts, minimizing waste while meeting the requirement.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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