LFCS Service Configuration Practice Question
A system administrator wants to configure a custom service to start automatically at boot. Which command accomplishes this?
⚠ Common exam trap
Watch out — candidates often confuse `systemctl start` (immediate runtime start) with `systemctl enable` (boot-time persistence), leading them to select option D when the question specifically asks for automatic boot-time configuration.
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 custom.service
The `systemctl enable custom.service` command creates the necessary symlinks in the systemd unit file directories (e.g., `/etc/systemd/system/multi-user.target.wants/`) so that the service is automatically started at boot. This is the correct method to configure a custom service for automatic startup in a systemd-based Linux distribution.
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 custom.service
Why it's wrong here
daemon-reload regenerates systemd's in-memory unit cache after unit files change on disk; it does not enable anything. The service would still be absent from boot targets. Reloading is correct after editing a unit file, before starting or enabling the revised unit.
- ✓
systemctl enable custom.service
Why this is correct
`systemctl enable custom.service` creates a symlink from the service unit file in `/etc/systemd/system` into the appropriate multi-user.target.wants directory, which instructs systemd to start the service automatically at boot. This satisfies the stem’s requirement for a custom service to be launched during the boot sequence without manual intervention, leveraging systemd’s dependency-based parallel startup mechanism.
- ✗
systemctl reenable custom.service
Why it's wrong here
Reenable re-installs the symlinks for an already-enabled unit; it does not enable a service that is currently disabled, so boot activation is not achieved. It is tempting because it manipulates the same symlink mechanism as enable, which is the command that actually creates the boot-time links.
- ✗
systemctl start custom.service
Why it's wrong here
Starting the unit now only launches it for the current session; it does not create the enablement symlinks under the target's wants directory that pull the service in at boot. Enabling is the correct mechanism. Starting is what you would run after a manual configuration change to apply it immediately.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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