Quick Answer
The answer is storage, because high disk I/O wait times directly indicate that the storage subsystem is the bottleneck. When the CPU issues read or write requests to the disk and must idle while waiting for those operations to complete, the system registers elevated I/O wait—a metric that measures the percentage of time the CPU is stalled waiting for data from storage. On the CompTIA ITF+ FC0-U61 exam, this concept tests your ability to differentiate between resource bottlenecks: high disk I/O wait points to storage, not CPU, memory, or network issues. A common trap is to assume high CPU usage means a CPU problem, but here the CPU is actually idle, waiting on slow disk response. Remember the memory tip: “I/O wait = storage gate”—if the CPU is waiting, the disk is the culprit.
This FC0-U61 practice question tests your understanding of it concepts and terminology. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company's email server is experiencing slow performance. The IT administrator notices high disk I/O wait times. Which component is most likely bottlenecked?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
CPU
Why wrong: High disk I/O wait does not necessarily indicate CPU bottleneck; CPU may be idle waiting for disk.
Storage
High disk I/O wait suggests that the storage subsystem (HDD/SSD) is unable to keep up with requests.
Network
Why wrong: Network bottleneck would show high network latency or packet loss, not disk I/O wait.
RAM
Why wrong: Low RAM can cause swapping, but disk I/O wait specifically points to storage speed.
Answer choices
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
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 does not necessarily indicate CPU bottleneck; CPU may be idle waiting for disk.
Storage
Why this is correct
High disk I/O wait suggests that the storage subsystem (HDD/SSD) is unable to keep up with requests.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Network
Why it's wrong here
Network bottleneck would show high network latency or packet loss, not disk I/O wait.
RAM
Why it's wrong here
Low RAM can cause swapping, but disk I/O wait specifically points to storage speed.
Common exam traps
The trap here is that 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.
Trap categories for this question
Command / output trap
Network bottleneck would show high network latency or packet loss, not disk I/O wait.
Detailed technical explanation
Disk I/O wait (iowait) is a Linux kernel metric that measures the percentage of time the CPU is idle while waiting for outstanding disk I/O requests to complete. In a real-world scenario, a misconfigured RAID array with a missing cache battery or a failing SSD can cause iowait to spike even with moderate throughput, as the storage controller enters a write-through mode that dramatically increases latency.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the FC0-U61 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
IT Concepts and Terminology — study guide chapter
Learn the concepts, then practise the questions
IT Concepts and Terminology practice questions
Targeted practice on this topic area only
All FC0-U61 questions
512 questions across all exam domains
CompTIA ITF+ FC0-U61 study guide
Full concept coverage aligned to exam objectives
FC0-U61 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise FC0-U61 questions linked to IT Concepts and Terminology.
Practise FC0-U61 questions linked to Infrastructure.
Practise FC0-U61 questions linked to Applications and Software.
Practise FC0-U61 questions linked to Software Development Concepts.
Practise FC0-U61 questions linked to Security.
Practise FC0-U61 questions linked to Database Fundamentals.
Practise FC0-U61 questions linked to FC0-U61 fundamentals.
Practise FC0-U61 questions linked to FC0-U61 scenario.
Practise FC0-U61 questions linked to FC0-U61 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
IT Concepts and Terminology — This question tests IT Concepts and Terminology — Read the scenario before looking for a memorised answer..
The correct answer is: 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 25, 2026
This FC0-U61 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-U61 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.