This LFCS practice question tests your understanding of operation of running systems. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO of the following commands can be used to display the current kernel ring buffer messages? (Select TWO.)
journalctl -k
Shows kernel messages from journal.
syslog -k
Why wrong: No such command.
dmesg
Directly reads kernel ring buffer.
cat /proc/kmsg
Why wrong: Requires root and is a different interface, not typical.
tail /var/log/messages
Why wrong: Shows syslog messages, not specifically kernel ring buffer.
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 -k
A is correct because `journalctl -k` queries the systemd journal for kernel messages only, displaying the current kernel ring buffer content. This is the modern way to access kernel logs on systems using systemd, equivalent to `dmesg` but with structured journal output.
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.
journalctl -k
Why this is correct
Shows kernel messages from journal.
Related concept
Read the scenario before looking for a memorised answer.
syslog -k
Why it's wrong here
No such command.
dmesg
Why this is correct
Directly reads kernel ring buffer.
Related concept
Read the scenario before looking for a memorised answer.
cat /proc/kmsg
Why it's wrong here
Requires root and is a different interface, not typical.
tail /var/log/messages
Why it's wrong here
Shows syslog messages, not specifically kernel ring buffer.
Common exam traps
The trap here is that candidates may confuse `cat /proc/kmsg` with `dmesg`, not realizing that `/proc/kmsg` is a one-time destructive read requiring root, while `dmesg` is the safe, standard command for non-destructive access to the kernel ring buffer.
Trap categories for this question
Command / output trap
No such command.
Detailed technical explanation
The kernel ring buffer is a fixed-size circular buffer in kernel memory that stores kernel log messages (printk output). `dmesg` reads this buffer via the `syslog` system call (SYSLOG_ACTION_READ) without consuming it, while `journalctl -k` reads from the systemd journal, which captures kernel messages via `/dev/kmsg` (a newer interface that allows multiple readers). On systems without systemd, `dmesg` is the primary tool; on systemd systems, both work, but `journalctl -k` provides additional filtering and structured output.
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 LFCS 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.
Operation of Running Systems — study guide chapter
Learn the concepts, then practise the questions
Operation of Running Systems practice questions
Targeted practice on this topic area only
All LFCS questions
513 questions across all exam domains
Linux Foundation Certified System Administrator LFCS study guide
Full concept coverage aligned to exam objectives
LFCS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise LFCS questions linked to User and Group Management.
Practise LFCS questions linked to Operation of Running Systems.
Practise LFCS questions linked to Essential Commands.
Practise LFCS questions linked to Networking.
Practise LFCS questions linked to Service Configuration.
Practise LFCS questions linked to Storage Management.
Practise LFCS questions linked to LFCS fundamentals.
Practise LFCS questions linked to LFCS scenario.
Practise LFCS questions linked to LFCS troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Operation of Running Systems — This question tests Operation of Running Systems — Read the scenario before looking for a memorised answer..
The correct answer is: journalctl -k — A is correct because `journalctl -k` queries the systemd journal for kernel messages only, displaying the current kernel ring buffer content. This is the modern way to access kernel logs on systems using systemd, equivalent to `dmesg` but with structured journal output.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 25, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.