XK0-006 Troubleshooting Practice Question
An administrator needs to check the kernel ring buffer for hardware error messages from the current boot. Which command displays this information?
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
✓
dmesg
dmesg displays the kernel ring buffer, which includes hardware-related messages from the current boot.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
vmstat -f
Why it's wrong here
vmstat -f reports fork counts, not kernel messages; the ring buffer is read with dmesg. It tempts because vmstat is a genuine system-monitoring tool showing kernel-related statistics, but it never exposes hardware error text from the current boot.
- ✗
journalctl -k -b 0
Why it's wrong here
journalctl -k -b 0 reads the systemd journal, not the kernel ring buffer; the kernel's own messages live in /dev/kmsg and are surfaced by dmesg. It is tempting because journalctl -k does filter kernel messages, but only those captured by systemd-journald, and -b 0 denotes the current boot rather than the ring buffer itself.
- ✗
cat /var/log/boot.log
Why it's wrong here
/var/log/boot.log records userspace service start-up output from the init system, not kernel ring buffer hardware errors. It is tempting because the filename suggests boot-time diagnostics, but it contains no kernel messages; dmesg reads the ring buffer directly. Systems without systemd may not even create this file.
- ✓
dmesg
Why this is correct
`dmesg` reads the kernel ring buffer directly, exposing hardware and driver messages logged during the current boot. This satisfies the stem's requirement to inspect boot-time hardware errors, unlike journal or log-file tools that may aggregate or filter kernel output.
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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.