- A
255.255.255.128 (/25)
Why wrong: /25 provides 126 usable hosts, still more than necessary.
- B
255.255.255.0 (/24)
Why wrong: /24 provides 254 usable hosts, which is far more than needed and wastes addresses.
- C
255.255.255.192 (/26)
/26 provides 62 usable hosts, sufficient for 50 hosts with minimal waste.
- D
255.255.255.224 (/27)
Why wrong: /27 provides only 30 usable hosts, which is insufficient.
Question 790 of 1,000
200-901 Network Fundamentals Practice Question
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 is configuring a new subnet for a branch office that requires 50 usable host addresses. The corporate network uses the 192.168.10.0/24 block. Which subnet mask should be used to meet the requirement with minimal waste?
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 (/26)
Option C is correct because a /26 subnet mask (255.255.255.192) provides 2^(32-26) = 64 total addresses, of which 62 are usable (subtracting network and broadcast addresses). This meets the requirement of 50 usable hosts with minimal waste, as the next smaller mask (/27) only offers 30 usable addresses, which is insufficient.
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.
- ✗
255.255.255.128 (/25)
Why it's wrong here
/25 provides 126 usable hosts, still more than necessary.
- ✗
255.255.255.0 (/24)
Why it's wrong here
/24 provides 254 usable hosts, which is far more than needed and wastes addresses.
- ✓
255.255.255.192 (/26)
Why this is correct
/26 provides 62 usable hosts, sufficient for 50 hosts with minimal waste.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
255.255.255.224 (/27)
Why it's wrong here
/27 provides only 30 usable hosts, which is insufficient.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often forget to subtract the two reserved addresses (network and broadcast) from the total host count, leading them to incorrectly select a /27 mask (which has 32 total addresses but only 30 usable) thinking it is sufficient for 50 hosts.
Detailed technical explanation
How to think about this question
The number of usable hosts in a subnet is calculated as 2^(32 - prefix_length) - 2, where the subtraction accounts for the network address (all host bits 0) and the broadcast address (all host bits 1). In IPv4, the subnet mask is applied via a bitwise AND operation with the IP address to derive the network prefix. Real-world scenarios like branch office subnetting often require balancing growth allowance with address conservation, making the /26 a common choice for 50-host networks.
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 200-901 question test?
Network Fundamentals — This question tests Network Fundamentals — 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 (/26) — Option C is correct because a /26 subnet mask (255.255.255.192) provides 2^(32-26) = 64 total addresses, of which 62 are usable (subtracting network and broadcast addresses). This meets the requirement of 50 usable hosts with minimal waste, as the next smaller mask (/27) only offers 30 usable addresses, which is insufficient.
What should I do if I get this 200-901 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: Jul 4, 2026
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.
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