Question 783 of 1,020

IP Addressing →hardMultiple ChoiceObjective-mapped

Choosing a Subnet Mask for 50 Devices: /26 (255.255.255.192) is Best

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 administrator is designing a new subnet scheme for a company with 4 departments: Sales (50 devices), HR (25 devices), IT (10 devices), and Management (5 devices). The company uses the 10.0.0.0/8 network. To minimize wasted IP addresses, which subnet mask should be used for 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.

A
255.255.255.0
Why wrong: A /24 subnet provides 254 usable hosts, which is far more than needed for 50 devices and would waste IP addresses.
B
255.255.255.192
A /26 subnet provides 62 usable hosts, which is sufficient for 50 devices and minimizes waste.
C
255.255.255.224
Why wrong: A /27 subnet provides 30 usable hosts, which is not enough for 50 devices.
D
255.255.255.240
Why wrong: A /28 subnet provides 14 usable hosts, which is far too few for 50 devices.

Full breakdown with real-world context →

Quick Answer

The answer is a /26 subnet mask, which is 255.255.255.192. This is the correct choice because to support 50 devices, you need at least 52 usable IP addresses—50 for the hosts plus 2 reserved for the network and broadcast addresses. A /26 subnet provides 62 usable hosts, making it the smallest subnet that comfortably accommodates 50 devices without wasting addresses, unlike a /25 which offers 126 hosts and would waste over half the range. On the CompTIA A+ Core 1 220-1201 exam, this tests your ability to calculate subnet sizes based on host requirements, often appearing in scenario-based questions where you must pick the most efficient mask from a list. A common trap is forgetting to add the 2 reserved addresses or choosing a /24 (254 hosts) out of habit, which wastes IP space. For a quick memory tip, remember that a /26 gives you 62 hosts—just think “2 to the 6th power minus 2” (64 minus 2) for the six host bits remaining after the 26 network bits.

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

The Sales department requires 50 usable IP addresses. A /26 subnet mask (255.255.255.192) provides 64 total addresses, with 62 usable addresses (2^6 - 2 = 62), which is the smallest subnet that can accommodate 50 devices without wasting IPs. This aligns with the goal of minimizing wasted addresses in the 10.0.0.0/8 network.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
255.255.255.0
Why it's wrong here
A /24 subnet provides 254 usable hosts, which is far more than needed for 50 devices and would waste IP addresses.
✓
255.255.255.192
Why this is correct
A /26 subnet provides 62 usable hosts, which is sufficient for 50 devices and minimizes 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
Why it's wrong here
A /27 subnet provides 30 usable hosts, which is not enough for 50 devices.
✗
255.255.255.240
Why it's wrong here
A /28 subnet provides 14 usable hosts, which is far too few for 50 devices.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the ability to calculate the smallest subnet that meets host requirements, and the trap here is that candidates may choose a mask that provides exactly 50 usable addresses (like /27 with 30 addresses) without accounting for the 2 reserved addresses (network and broadcast), or they may overestimate and pick a /24 mask out of habit.

Detailed technical explanation

How to think about this question

The subnet mask 255.255.255.192 corresponds to a /26 prefix length, meaning 6 bits are used for host addresses (2^6 = 64 total, minus network and broadcast addresses). In a real-world scenario, network administrators often use Variable Length Subnet Masking (VLSM) to allocate subnets based on exact host requirements, as defined in RFC 1878, to conserve IP space in a private 10.0.0.0/8 network.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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.

Visual reference

What to study next

Got this wrong? Here's your next step.

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

Questions learners often ask

What does this 220-1201 question test?

IP Addressing — This question tests IP Addressing — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: 255.255.255.192 — The Sales department requires 50 usable IP addresses. A /26 subnet mask (255.255.255.192) provides 64 total addresses, with 62 usable addresses (2^6 - 2 = 62), which is the smallest subnet that can accommodate 50 devices without wasting IPs. This aligns with the goal of minimizing wasted addresses in the 10.0.0.0/8 network.

What should I do if I get this 220-1201 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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?

Read the scenario before looking for a memorised answer.

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