- A
journalctl -k
journalctl -k shows kernel messages from the journal.
- B
cat /proc/kmsg
Why wrong: /proc/kmsg requires root and is not recommended.
- C
tail -f /var/log/boot.log
Why wrong: boot.log contains some messages but not the kernel ring buffer.
- D
dmesg
dmesg displays kernel ring buffer messages.
- E
vmstat -f
Why wrong: vmstat -f shows fork statistics.
Question 836 of 981
XK0-005 Troubleshooting Practice Question
This XK0-005 practice question tests your understanding of troubleshooting. 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 system is experiencing boot failures. The administrator wants to view kernel messages from the current boot to diagnose the issue. Which two commands can be used to see these messages? (Choose two.)
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
✓
journalctl -k
`journalctl -k` displays kernel messages from the current boot by querying the systemd journal, which logs kernel ring buffer messages persistently. `dmesg` reads the kernel ring buffer directly and shows messages from the current boot cycle. Both commands provide the kernel diagnostic output needed to troubleshoot boot failures.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
journalctl -k
Why this is correct
journalctl -k shows kernel messages from the journal.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
cat /proc/kmsg
Why it's wrong here
/proc/kmsg requires root and is not recommended.
- ✗
tail -f /var/log/boot.log
Why it's wrong here
boot.log contains some messages but not the kernel ring buffer.
- ✓
dmesg
Why this is correct
dmesg displays kernel ring buffer messages.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
vmstat -f
Why it's wrong here
vmstat -f shows fork statistics.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse `dmesg` with `cat /proc/kmsg` or think `boot.log` contains kernel messages, when in fact `dmesg` and `journalctl -k` are the standard tools for viewing kernel ring buffer output from the current boot.
Trap categories for this question
Command / output trap
vmstat -f shows fork statistics.
Detailed technical explanation
How to think about this question
The kernel ring buffer is a fixed‑size circular buffer in memory that stores kernel log messages (printk output). `dmesg` reads this buffer via the `syslog` system call or `/dev/kmsg`, while `journalctl -k` reads the same data from the systemd journal, which captures and persists the kernel ring buffer at boot time. In modern systems, the journal may contain more complete history if `Storage=persistent` is set in `/etc/systemd/journald.conf`.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the XK0-005 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Troubleshooting — study guide chapter
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: journalctl -k — `journalctl -k` displays kernel messages from the current boot by querying the systemd journal, which logs kernel ring buffer messages persistently. `dmesg` reads the kernel ring buffer directly and shows messages from the current boot cycle. Both commands provide the kernel diagnostic output needed to troubleshoot boot failures.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This XK0-005 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 XK0-005 exam.
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