The answer is 255.255.255.192, which is a /26 subnet mask. This is the correct VLSM subnet mask for 50 devices because it provides 62 usable host addresses, the smallest power of two that accommodates the required 50 hosts without excessive waste. In variable-length subnet masking, you always allocate the largest subnet first, so the Sales department’s need for 50 devices dictates a /26 prefix, while smaller subnets like /27 (30 usable hosts) or /28 (14 usable hosts) would fall short. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to apply VLSM to minimize IP waste in a real-world scenario, often appearing as part of a multi-department subnetting problem. A common trap is forgetting to subtract the network and broadcast addresses when counting usable hosts, or assuming a /25 (126 hosts) is needed, which wastes addresses. For a quick memory tip, remember that a /26 gives you 64 total addresses minus 2 for network and broadcast, leaving exactly 62—plenty for 50 devices, and the “6” in /26 can remind you of the 6 bits for hosts (2^6 = 64).
220-1201 IP Addressing Practice Question
This 220-1201 practice question tests your understanding of ip addressing. 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 engineer is designing a subnet scheme for a company with three departments: Sales (50 devices), HR (20 devices), and IT (10 devices). The company uses the 10.0.0.0/24 network. To minimize waste, the engineer decides to use variable-length subnet masking (VLSM). Which of the following subnet masks should be assigned to the Sales department?
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.
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
With VLSM, the largest subnet should be assigned first. Sales needs 50 usable addresses, so a /26 subnet (255.255.255.192) provides 62 usable addresses, which is sufficient and efficient. Smaller subnets would not accommodate 50 devices.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
255.255.255.128
Why it's wrong here
Incorrect. A /25 provides 126 usable addresses, which is more than needed and wastes addresses.
✓
255.255.255.192
Why this is correct
Correct. A /26 provides 62 usable addresses, enough for 50 devices with minimal waste.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Incorrect. A /27 provides only 30 usable addresses, which is insufficient for 50 devices.
✗
255.255.255.240
Why it's wrong here
Incorrect. A /28 provides only 14 usable addresses, far too few for Sales.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
IP Addressing — This question tests IP Addressing — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: 255.255.255.192 — With VLSM, the largest subnet should be assigned first. Sales needs 50 usable addresses, so a /26 subnet (255.255.255.192) provides 62 usable addresses, which is sufficient and efficient. Smaller subnets would not accommodate 50 devices.
What should I do if I get this 220-1201 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
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.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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