The answer is `journalctl -u sshd -n 20` and `grep '^username:' /etc/passwd`. The first command is correct because when SSH login troubleshooting on Linux, the systemd journal holds the most recent, time-stamped logs for the SSH daemon, allowing you to spot authentication failures or configuration errors even when the service appears to be running. The second command directly checks whether the user account exists in the local password database, which is a common cause of login rejection despite network connectivity being fine. On the CompTIA Linux+ XK0-005 exam, this question tests your ability to distinguish between service-level logs and account-level verification; a common trap is to check network tools like `ping` or `ss` when the issue is actually user-related. Remember the memory tip: “Logs for the daemon, grep for the person.”
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 user cannot log in to a Linux system via SSH, but the SSH service is running and network connectivity is fine. Which TWO commands should the administrator use to troubleshoot the issue? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
journalctl -u sshd -n 20
Option A is correct because `journalctl -u sshd -n 20` displays the last 20 log entries for the SSH daemon (sshd). This allows the administrator to see authentication failures, configuration errors, or other SSH-specific issues that prevent login, even when the service is running and network connectivity is fine.
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 -u sshd -n 20
Why this is correct
View recent SSH daemon logs for authentication errors.
Related concept
Read the scenario before looking for a memorised answer.
✗
cat /etc/ssh/sshd_config
Why it's wrong here
Checking config is useful but not the first two steps; logs and basic user info are quicker.
✗
passwd -S username
Why it's wrong here
Shows account status (locked/unlocked), but that is a possible cause, but less common than shell issues and logs.
✗
ss -tlnp | grep :22
Why it's wrong here
Confirms SSH is listening, but already known to be running.
✓
grep '^username:' /etc/passwd
Why this is correct
Check if the user has a valid shell set in /etc/passwd.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose `ss -tlnp | grep :22` (Option D) because they think verifying the port is listening is the first step, but the question explicitly states the service is running and network is fine, making this command redundant and not a troubleshooting step for the user-specific login failure.
Trap categories for this question
Command / output trap
Shows account status (locked/unlocked), but that is a possible cause, but less common than shell issues and logs.
Detailed technical explanation
How to think about this question
The `journalctl` command queries the systemd journal, which logs detailed SSH authentication events such as 'Failed password for username', 'Connection closed by authenticating user', or 'User not allowed because account is locked'. In contrast, `grep '^username:' /etc/passwd` (Option E) checks if the user account exists in the local password database; a missing or misconfigured entry (e.g., invalid shell, home directory issues) can cause SSH to reject the login even if the service is running. Real-world scenarios often involve PAM modules or `sshd_config` directives like `AllowUsers` that silently deny access, which only logs or configuration inspection can reveal.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
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 -u sshd -n 20 — Option A is correct because `journalctl -u sshd -n 20` displays the last 20 log entries for the SSH daemon (sshd). This allows the administrator to see authentication failures, configuration errors, or other SSH-specific issues that prevent login, even when the service is running and network connectivity is fine.
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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Question Discussion
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