hardMultiple ChoiceObjective-mapped
XK0-006 Practice Question: A Linux administrator is troubleshooting a server…
A Linux administrator is troubleshooting a server that is running slowly. The 'sar -q' command shows a run queue length of 12 and a load average of 8.5. The CPU utilization is 90% idle. Which of the following is the most likely cause of the performance issue?
⚠ Common exam trap
The trap here is that candidates see a high load average and assume CPU overload, but the 90% idle CPU reveals the load is from I/O-waiting processes, not CPU contention.
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
✓
The disk I/O subsystem is a bottleneck, causing processes to wait for I/O.
The 'sar -q' output shows a high run queue length (12) and load average (8.5) despite 90% CPU idle. This indicates that processes are in an uninterruptible sleep state (D state) waiting for I/O, not contending for CPU. A disk I/O bottleneck causes processes to queue for I/O completion, inflating the load average while CPU remains idle, making D the correct answer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The CPU is overloaded and needs to be upgraded.
Why it's wrong here
CPU is 90% idle, so it is not overloaded.
- ✗
The network interface is saturated.
Why it's wrong here
Network saturation would not cause high run queue with idle CPU.
- ✗
The system is low on memory and swapping heavily.
Why it's wrong here
Memory pressure would show high swap usage and possibly high I/O wait, but the primary indicator is high run queue with idle CPU.
- ✓
The disk I/O subsystem is a bottleneck, causing processes to wait for I/O.
Why this is correct
High run queue with idle CPU typically means I/O wait; processes are in 'D' state waiting for disk.
Go deeper
Related to this question
Learn chapter
Linux Fundamentals and History
Key term
Output
In IT service management, output is the result or deliverable produced by a process, system, or component, such as data, reports, or services delivered to a customer.
Key term
Linux
Linux is an open-source operating system that manages computer hardware and software, widely used in servers, desktops, and embedded systems.
About these practice questions
Courseiva writes every XK0-006 question from scratch — 979 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 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 XK0-006 exam.