LFCS Operation of Running Systems Practice Question
An administrator wants to ensure that a service starts automatically after a system crash. Which systemd command should be used?
⚠ Common exam trap
Watch out — candidates often confuse `systemctl start` (immediate, one-time start) with `systemctl enable` (persistent boot-time start), leading them to choose option D, which does not survive a reboot or crash.
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
✓
systemctl enable service
The `systemctl enable service` command creates the necessary symlinks in the systemd unit configuration directories (e.g., `/etc/systemd/system/multi-user.target.wants/`) so that the service is automatically started at boot. This includes recovery after a system crash, because the crash triggers a reboot, and the enabled service will be started as part of the normal boot process.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
systemctl daemon-reload
Why it's wrong here
daemon-reload only re-reads unit files after edits; it neither enables a unit at boot nor restarts it after a crash. It is tempting because administrators routinely run it after changing service definitions, and it is the correct choice when new or modified unit files must be picked up without rebooting.
- ✓
systemctl enable service
Why this is correct
systemctl enable creates the symlinks that pull the unit into the appropriate target's wants directory, so systemd starts the service automatically at boot, including after a crash-induced reboot. Starting it now would not survive a restart.
- ✗
systemctl mask service
Why it's wrong here
Masking links the unit to /dev/null, preventing both manual and automatic activation, so the service cannot start at all after a crash. It is tempting because masking is genuinely used to block unwanted services from being started by dependencies or sockets, but that is the opposite of ensuring automatic restart.
- ✗
systemctl start service
Why it's wrong here
start launches the unit once in the current session only; it sets no enablement or restart behaviour, so a crash leaves the service down. It is tempting because it is the everyday command for bringing a service up immediately, and it would be right when the unit is already enabled and merely needs starting now.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.