The answer is the combination of `Restart=on-failure` and `WantedBy=multi-user.target`. `Restart=on-failure` is the directive that tells systemd to automatically restart the service whenever it crashes or exits with a non-zero code, covering the "restart on failure" requirement. Meanwhile, `WantedBy=multi-user.target` ensures the service is enabled to start at boot, which includes automatic startup after a system crash, because systemd processes all enabled units during the boot sequence. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your understanding of systemd unit directives and the distinction between service-level restart policies and install-level boot dependencies. A common trap is confusing `Restart=always` with `Restart=on-failure`—remember that `always` restarts even on clean exits, while `on-failure` is the precise choice for crash recovery. For a memory tip, think "failure fires restart, multi-user starts after crash."
LFCS Operation of Running Systems Practice Question
This LFCS practice question tests your understanding of operation of running systems. 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 system administrator needs to ensure that a specific service, 'myapp', starts automatically after a system crash and also restarts if it fails. Which systemd unit directive should be used to achieve this behavior?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Restart=on-failure and WantedBy=multi-user.target
Option C is correct because the combination of `Restart=on-failure` ensures the service restarts automatically if it exits with a non-zero exit code or is terminated by a signal, and `WantedBy=multi-user.target` creates a dependency that starts the service at boot, including after a system crash. This satisfies both requirements: automatic start after crash (via systemd's dependency-based boot) and restart on failure (via the Restart directive).
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.
✗
RemainAfterExit=yes
Why it's wrong here
RemainAfterExit=yes only keeps the service unit active after the main process exits, but does not restart it.
✗
Restart=always
Why it's wrong here
Restart=always restarts the service regardless of exit status, but it also restarts if the admin stops it manually, which is not desired.
✓
Restart=on-failure and WantedBy=multi-user.target
Why this is correct
Restart=on-failure restarts the service only if it fails (non-zero exit), and WantedBy=multi-user.target ensures it starts at boot.
Related concept
Read the scenario before looking for a memorised answer.
✗
ExecStopPost=/bin/systemctl restart myapp.service
Why it's wrong here
ExecStopPost runs a command after the service stops, but it is not the standard way to handle automatic restart on failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `Restart=always` with `Restart=on-failure`, not realizing that `always` restarts even on manual stops, which violates the typical requirement to only restart on failure, and they may overlook that `WantedBy=multi-user.target` is necessary for automatic start after a crash.
Trap categories for this question
Command / output trap
ExecStopPost runs a command after the service stops, but it is not the standard way to handle automatic restart on failure.
Detailed technical explanation
How to think about this question
Under the hood, systemd's `Restart=` directive uses the service's exit status and signal information to decide whether to restart; `on-failure` triggers restart for non-zero exit codes, abnormal signals, and timeouts, but not for clean exits like a manual `systemctl stop`. The `WantedBy=multi-user.target` creates a symbolic link in `/etc/systemd/system/multi-user.target.wants/`, ensuring the service is started as part of the default boot target, which includes recovery after a crash. A real-world scenario is a database service that must restart after a kernel panic but should not restart if an admin intentionally stops it for maintenance.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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.
Operation of Running Systems — This question tests Operation of Running Systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Restart=on-failure and WantedBy=multi-user.target — Option C is correct because the combination of `Restart=on-failure` ensures the service restarts automatically if it exits with a non-zero exit code or is terminated by a signal, and `WantedBy=multi-user.target` creates a dependency that starts the service at boot, including after a system crash. This satisfies both requirements: automatic start after crash (via systemd's dependency-based boot) and restart on failure (via the Restart directive).
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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