- A
30
Why wrong: 30 usable addresses correspond to a /27 subnet (5 host bits), which is insufficient for 50 devices.
- B
62
Correct. /26 provides 62 usable addresses, enough for 50 devices with room for growth.
- C
126
Why wrong: 126 usable addresses come from a /25 subnet (7 host bits), which is larger than necessary.
- D
254
Why wrong: 254 usable addresses are from a /24 subnet (8 host bits), which is much larger than required.
Question 264 of 520
N10-009 Networking Concepts Practice Question
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 network engineer is designing a subnet to accommodate 50 devices in a single broadcast domain. The engineer uses a /26 subnet mask. How many usable host addresses are available?
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
✓
62
A /26 subnet mask provides 2^(32-26) = 64 total addresses. Subtracting the network and broadcast addresses leaves 62 usable host addresses. This is sufficient for 50 devices in a single broadcast domain.
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.
- ✗
30
Why it's wrong here
30 usable addresses correspond to a /27 subnet (5 host bits), which is insufficient for 50 devices.
When this WOULD be correct
This would be correct if the question specified a /27 subnet mask (255.255.255.224), which provides 32 total addresses minus 2 = 30 usable hosts.
- ✓
62
Why this is correct
Correct. /26 provides 62 usable addresses, enough for 50 devices with room for growth.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
126
Why it's wrong here
126 usable addresses come from a /25 subnet (7 host bits), which is larger than necessary.
When this WOULD be correct
This option would be correct if the question specified a /25 subnet mask (255.255.255.128) instead of /26. For example: 'A network engineer is designing a subnet to accommodate 100 devices. The engineer uses a /25 subnet mask. How many usable host addresses are available?'
- ✗
254
Why it's wrong here
254 usable addresses are from a /24 subnet (8 host bits), which is much larger than required.
When this WOULD be correct
This option would be correct if the question specified a /24 subnet mask (e.g., 'How many usable host addresses are available with a /24 subnet mask?').
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓62Correct answer▾
Why this is correct
Correct. /26 provides 62 usable addresses, enough for 50 devices with room for growth.
✗30Wrong answer — click to see why▾
Why this is wrong here
A /26 subnet provides 2^(32-26) = 64 total addresses, with 2 reserved for network and broadcast, leaving 62 usable. Option A (30) corresponds to a /27 subnet, not /26.
★ When this WOULD be the correct answer
This would be correct if the question specified a /27 subnet mask (255.255.255.224), which provides 32 total addresses minus 2 = 30 usable hosts.
Why candidates choose this
Candidates often miscalculate by subtracting 2 from 32 (thinking /26 gives 32 addresses) or confuse /26 with /27 due to common subnetting errors.
✗126Wrong answer — click to see why▾
Why this is wrong here
A /26 subnet mask provides 64 total addresses, with 62 usable host addresses (2^6 - 2 = 62). Option C (126) corresponds to a /25 subnet mask, which is not used in this question.
★ When this WOULD be the correct answer
This option would be correct if the question specified a /25 subnet mask (255.255.255.128) instead of /26. For example: 'A network engineer is designing a subnet to accommodate 100 devices. The engineer uses a /25 subnet mask. How many usable host addresses are available?'
Why candidates choose this
Candidates may mistakenly calculate 2^7 - 2 = 126, confusing the /26 subnet (6 host bits) with a /25 subnet (7 host bits), or they might forget to subtract the network and broadcast addresses.
✗254Wrong answer — click to see why▾
Why this is wrong here
A /26 subnet mask provides 64 total addresses, with 62 usable host addresses (64 - 2 for network and broadcast). Option D (254) corresponds to a /24 subnet mask, not /26.
★ When this WOULD be the correct answer
This option would be correct if the question specified a /24 subnet mask (e.g., 'How many usable host addresses are available with a /24 subnet mask?').
Why candidates choose this
Candidates may confuse subnet masks, thinking /26 provides 254 usable addresses due to misremembering the host bits or incorrectly applying the formula 2^(32-26)-2.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often forget to subtract the network and broadcast addresses, or they confuse the total addresses (64) with usable addresses (62), leading them to pick 64 or misapply the formula for a different prefix length.
Detailed technical explanation
How to think about this question
The /26 mask (255.255.255.192) borrows 2 bits from the host portion of a Class C address, creating 4 subnets each with 64 addresses. The usable host count is always 2^(32-prefix) - 2, where the -2 accounts for the network and broadcast addresses. In real-world scenarios, engineers must also account for gateway addresses, DHCP reservations, and management IPs when sizing subnets.
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.
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FAQ
Questions learners often ask
What does this N10-009 question test?
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 62 — A /26 subnet mask provides 2^(32-26) = 64 total addresses. Subtracting the network and broadcast addresses leaves 62 usable host addresses. This is sufficient for 50 devices in a single broadcast domain.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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