hardMultiple Choice
FC0-U71 Practice Question: A company's email server is experiencing slow…
A company's email server is experiencing slow performance. The IT administrator notices high disk I/O wait times. Which component is most likely bottlenecked?
⚠ Common exam trap
Watch out — candidates often confuse high disk I/O wait with a CPU bottleneck, because the CPU appears busy in monitoring tools, but iowait specifically indicates the CPU is stalled waiting for storage, not that it is processing at capacity.
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
✓
Storage
High disk I/O wait times indicate that the storage subsystem is struggling to keep up with read/write requests, causing the CPU to idle while waiting for data from the disk. This is a classic symptom of a storage bottleneck, not a CPU, network, or memory issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
CPU
Why it's wrong here
High disk I/O wait means processes are blocked awaiting storage reads and writes; the CPU is idle during that wait, not saturated, so it is not the bottleneck. CPU would be the culprit when utilisation sits near 100% with low wait times.
- ✓
Storage
Why this is correct
High disk I/O wait times indicate processes are queuing for disk access rather than CPU or memory contention. The storage subsystem cannot service requests fast enough, so the bottleneck lies with the disk or its controller, not the processor, RAM or network interface.
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Network
Why it's wrong here
High disk I/O wait times point to the storage subsystem, not the network; the NIC's throughput and latency counters would show saturation instead. Network bandwidth becomes the bottleneck when link utilisation peaks or packet loss rises, which is not what the stem describes.
- ✗
RAM
Why it's wrong here
RAM exhaustion manifests as paging and swap activity, not elevated disk I/O wait on the data volume itself; memory pressure would show as high swap-in/swap-out and low free memory. Adding RAM is the fix when the working set exceeds installed capacity, causing swapping.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This FC0-U71 practice question is part of Courseiva's free CompTIA 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 FC0-U71 exam.