Quick Answer
The answer is 255.255.255.192, or a /26 subnet mask, because it provides exactly 62 usable host addresses—the minimum that satisfies the requirement for 50 devices while avoiding waste. This is calculated using the formula 2^(32-26) - 2, which subtracts the network and broadcast addresses from the total 64 addresses in the block. On the CompTIA Network+ N10-009 exam, this tests your ability to match subnet masks to real-world capacity needs, often appearing in scenario-based questions where you must choose the most efficient mask. A common trap is selecting a /27, which only offers 30 usable hosts—far too few—or a /25 with 126 hosts, which wastes over half the address space. To remember, think of the /26 as the “sweet spot” for midsize workgroups: it doubles the /27’s capacity while staying leaner than a /25. A quick memory tip: “26 hosts 62, just enough to fix.”
This N10-009 practice question tests your understanding of networking concepts. 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 company needs a subnet that will support exactly 50 devices. Which subnet mask provides the minimum number of usable host addresses while still accommodating the requirement?
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.
255.255.255.128 (/25)
Why wrong: /25 provides 126 usable hosts, which is more than needed and wastes addresses.
255.255.255.192 (/26)
/26 provides 62 usable hosts, which is the smallest subnet that can accommodate 50 devices.
255.255.255.224 (/27)
Why wrong: /27 only provides 30 usable hosts, which is too few.
255.255.255.240 (/28)
Why wrong: /28 only provides 14 usable hosts, far too few.
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)
Option B (255.255.255.192, /26) provides 2^(32-26) - 2 = 62 usable host addresses, which is the smallest subnet that supports exactly 50 devices. A /27 yields only 30 usable addresses (too few), while a /25 yields 126 usable addresses (wasteful). The requirement is to minimize waste while meeting the need.
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.
255.255.255.128 (/25)
Why it's wrong here
/25 provides 126 usable hosts, which is more than needed and wastes addresses.
255.255.255.192 (/26)
Why this is correct
/26 provides 62 usable hosts, which is the smallest subnet that can accommodate 50 devices.
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
/27 only provides 30 usable hosts, which is too few.
255.255.255.240 (/28)
Why it's wrong here
/28 only provides 14 usable hosts, far too few.
Common exam traps
Cisco often tests the candidate's ability to distinguish between total addresses and usable host addresses, with the trap being that candidates forget to subtract the network and broadcast addresses, leading them to incorrectly select a /27 (which has 32 total addresses but only 30 usable).
Detailed technical explanation
The usable host count is derived from the formula 2^(32 - prefix_length) - 2, where the two subtracted addresses are the network address (all host bits 0) and the broadcast address (all host bits 1). In IPv4 subnetting, the /26 mask (255.255.255.192) borrows 2 bits from the host portion of a /24, creating 4 subnets each with 62 usable addresses. Real-world scenarios like VLAN sizing or point-to-point links require precise subnet selection to avoid IP exhaustion or waste.
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
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
The correct answer is: 255.255.255.192 (/26) — Option B (255.255.255.192, /26) provides 2^(32-26) - 2 = 62 usable host addresses, which is the smallest subnet that supports exactly 50 devices. A /27 yields only 30 usable addresses (too few), while a /25 yields 126 usable addresses (wasteful). The requirement is to minimize waste while meeting the need.
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 11, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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