This XK0-005 practice question tests your understanding of system management. 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 Linux administrator is troubleshooting a service that fails to start. Which THREE files or commands should be checked to diagnose the issue? (Select THREE.)
dmesg
Why wrong: Kernel ring buffer, not directly related to service failures.
journalctl -u service-name
Shows service-specific logs from journald.
/var/log/messages (or /var/log/syslog)
General system logs may contain error messages.
/etc/rc.local
Why wrong: Legacy script, not typically used for service startup.
systemctl status service-name
Shows current status and recent log entries.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
journalctl -u service-name
B is correct because `journalctl -u service-name` displays the systemd journal logs specifically for that service, which includes detailed error messages, timestamps, and status changes that are essential for diagnosing why the service failed to start. This command is the primary tool for viewing service-specific logs in modern systemd-based Linux distributions.
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.
dmesg
Why it's wrong here
Kernel ring buffer, not directly related to service failures.
journalctl -u service-name
Why this is correct
Shows service-specific logs from journald.
Related concept
Read the scenario before looking for a memorised answer.
/var/log/messages (or /var/log/syslog)
Why this is correct
General system logs may contain error messages.
Related concept
Read the scenario before looking for a memorised answer.
/etc/rc.local
Why it's wrong here
Legacy script, not typically used for service startup.
systemctl status service-name
Why this is correct
Shows current status and recent log entries.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
CompTIA often tests the distinction between kernel-level logs (dmesg) and service-level logs (journalctl), and the trap here is that candidates may confuse `dmesg` with service troubleshooting because it shows boot-time messages, but it does not capture service-specific failures.
Detailed technical explanation
Under the hood, `journalctl -u service-name` reads from the systemd journal, a binary log stored in `/var/log/journal/` or `/run/log/journal/`, which captures stdout, stderr, and syslog messages from the service's unit. The `-u` flag filters entries by the unit name, allowing precise troubleshooting without parsing the entire log. In a real-world scenario, a service might fail due to a missing dependency or a configuration syntax error, and the journal will show the exact exit code and error message, such as 'Main process exited, code=exited, status=1/FAILURE'.
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 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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
System Management — This question tests System Management — Read the scenario before looking for a memorised answer..
The correct answer is: journalctl -u service-name — B is correct because `journalctl -u service-name` displays the systemd journal logs specifically for that service, which includes detailed error messages, timestamps, and status changes that are essential for diagnosing why the service failed to start. This command is the primary tool for viewing service-specific logs in modern systemd-based Linux distributions.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 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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