XK0-006 Troubleshooting Practice Question
An administrator notices that a critical application server has become extremely slow, and load average has climbed above 40 on a 4-core system. The administrator wants to identify whether the bottleneck is CPU contention or processes stuck in uninterruptible sleep. (Choose two.)
⚠ Common exam trap
The trap here is treating a high load average as proof of CPU exhaustion when blocked-on-I/O tasks inflate it just as much as runnable ones.
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
✓
Run vmstat 1 and observe the r and b columns.
Load average counts both runnable and uninterruptible-sleep tasks, so a high value alone does not reveal the cause. top exposes per-process state letters alongside load averages, and vmstat's r and b columns quantify runnable versus blocked tasks over time. Memory, CPU topology, and filesystem checks do not separate the two candidate bottlenecks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Run vmstat 1 and observe the r and b columns.
Why this is correct
vmstat reports the number of runnable processes in the r column and processes blocked in uninterruptible sleep in the b column. A persistently high r points to CPU saturation, while a high b points to I/O blocking. Sampling every second reveals which condition dominates.
- ✗
Run df -h and check whether any filesystem is at 100 percent utilization.
Why it's wrong here
A full filesystem can cause application errors and slow writes, but df does not reveal process states or run queue depth. It is a useful check in a broader investigation, yet it cannot discriminate between CPU contention and processes blocked in uninterruptible sleep, which is the distinction required here.
- ✗
Run lscpu and verify the number of logical CPUs and their current frequency.
Why it's wrong here
lscpu describes CPU topology and capabilities but does not report current load or process states. Knowing there are four cores confirms the load average is roughly ten times the core count, which the administrator already inferred, but it provides no evidence about whether processes are runnable or blocked.
- ✓
Run top and examine the load average fields and the per-process state column.
Why this is correct
top shows the 1, 5, and 15 minute load averages plus each process's state letter. A D state indicates uninterruptible sleep, typically blocked on I/O, while R states with high CPU percentages indicate CPU contention. Together these distinguish the two scenarios on the same screen.
- ✗
Run free -m and compare the total and used memory values.
Why it's wrong here
free reports memory and swap utilization, which can contribute to slowness but does not separate CPU contention from uninterruptible sleep. High memory use may coexist with either bottleneck. It does not show per-process states or run queue depth, so it cannot answer the specific question posed.
Go deeper
Related to this question
Learn chapter
Navigating the Filesystem
Key term
Value
Value is the perceived worth, benefit, or usefulness that a service, product, or activity delivers to stakeholders, especially customers and the business.
Key term
Process
In IT service management, a process is a structured set of activities designed to accomplish a specific objective, such as managing incidents or changes, by transforming inputs into defined outputs.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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