200-901 Network Fundamentals Practice Question
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?
⚠ Common exam trap
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.
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)
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.
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.
- ✗
255.255.255.224 (/27)
Why it's wrong here
/27 provides only 30 usable hosts, which is insufficient.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.