This LFCS practice question tests your understanding of service configuration. 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.
Exhibit
Refer to the exhibit.
Output of `journalctl -u sshd.service --no-pager -p err`:
Jul 15 09:23:45 server sshd[1234]: Failed to start OpenSSH server daemon
Jul 15 09:23:45 server sshd[1234]: sshd.service: main process exited, code=exited, status=255/n/a
Jul 15 09:23:45 server sshd[1234]: Unit sshd.service entered failed state.
Refer to the exhibit.
Output of `journalctl -u sshd.service --no-pager -p err`:
Jul 15 09:23:45 server sshd[1234]: Failed to start OpenSSH server daemon
Jul 15 09:23:45 server sshd[1234]: sshd.service: main process exited, code=exited, status=255/n/a
Jul 15 09:23:45 server sshd[1234]: Unit sshd.service entered failed state.
A
SSH server is masked
Why wrong: Masked would show 'masked' status, not in log.
B
SSH server is running with errors
Why wrong: Log says failed state, not running.
C
SSH server stopped normally
Why wrong: Exit code 255 and failed state indicate abnormal exit.
D
SSH server failed to start due to configuration error
Exit status 255 typically indicates a configuration problem.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SSH server failed to start due to configuration error
The log shows that the SSH service failed to start because of a configuration error. Specifically, the log entry indicates a syntax error or invalid directive in the SSH daemon configuration file (typically /etc/ssh/sshd_config), which prevents the service from binding to the port and starting. This is a common issue when editing the configuration file manually, as the SSH daemon validates its configuration at startup and will refuse to run if any errors are found.
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.
✗
SSH server is masked
Why it's wrong here
Masked would show 'masked' status, not in log.
✗
SSH server is running with errors
Why it's wrong here
Log says failed state, not running.
✗
SSH server stopped normally
Why it's wrong here
Exit code 255 and failed state indicate abnormal exit.
✓
SSH server failed to start due to configuration error
Why this is correct
Exit status 255 typically indicates a configuration problem.
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 confuse a service that fails to start due to a configuration error with a service that is running but has errors, leading them to select option B instead of D.
Trap categories for this question
Command / output trap
Masked would show 'masked' status, not in log.
Detailed technical explanation
How to think about this question
The SSH daemon (sshd) reads its configuration from /etc/ssh/sshd_config at startup and performs a syntax check; if an invalid directive (e.g., a typo like 'PermitRootLogin yes' misspelled as 'PermitRootLogon') or an incorrect value is found, sshd will log the error and exit with a non-zero status. This behavior is enforced by the -t flag (test mode) which can be run manually via 'sshd -t' to validate the configuration before restarting the service. In real-world scenarios, forgetting to run this test after editing the config file can lead to an accidental lockout from remote access, especially when the SSH server is the only management interface.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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.
Service Configuration — This question tests Service Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: SSH server failed to start due to configuration error — The log shows that the SSH service failed to start because of a configuration error. Specifically, the log entry indicates a syntax error or invalid directive in the SSH daemon configuration file (typically /etc/ssh/sshd_config), which prevents the service from binding to the port and starting. This is a common issue when editing the configuration file manually, as the SSH daemon validates its configuration at startup and will refuse to run if any errors are found.
What should I do if I get this LFCS 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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