Service Configuration practice questions

A system administrator configures a web server using systemd. After creating a custom service unit file, the administrator runs `systemctl daemon-reload` but the service still fails to start with a 'Unit not found' error. What is the most likely cause?

Trap 1: The administrator forgot to run `systemctl enable` before starting…

Enable creates symlinks for automatic start, but is not required for manual start.

Trap 2: The administrator is not in the 'systemd' group.

No special group is required to manage systemd services; root or sudo is sufficient.

Trap 3: The service name was misspelled in the `systemctl start` command.

While possible, the 'Unit not found' error specifically indicates the unit file is not known to systemd, not a spelling mistake.

A
The administrator forgot to run `systemctl enable` before starting the service.
Why wrong: Enable creates symlinks for automatic start, but is not required for manual start.
B
The unit file is placed in /usr/lib/systemd/system/ instead of /etc/systemd/system/.
Unit files for custom services should be in /etc/systemd/system/; /usr/lib/systemd/system/ is for distribution-provided units.
C
The administrator is not in the 'systemd' group.
Why wrong: No special group is required to manage systemd services; root or sudo is sufficient.
D
The service name was misspelled in the `systemctl start` command.
Why wrong: While possible, the 'Unit not found' error specifically indicates the unit file is not known to systemd, not a spelling mistake.

Question 2hardmultiple choice

A server runs a custom application that listens on TCP port 8080. The administrator wants to ensure the application starts automatically on boot and restarts if it crashes. Which systemd unit file directive should be used to achieve the restart behavior?

Trap 1: RestartSec=5

RestartSec sets the delay before restart, but does not enable restarting.

Trap 2: Type=notify

Type=notify is used for services that notify systemd when they are ready, unrelated to restart.

Trap 3: RemainAfterExit=yes

RemainAfterExit keeps the service as active even if the main process exits, but does not restart it.

A
RestartSec=5
Why wrong: RestartSec sets the delay before restart, but does not enable restarting.
B
Type=notify
Why wrong: Type=notify is used for services that notify systemd when they are ready, unrelated to restart.
C
RemainAfterExit=yes
Why wrong: RemainAfterExit keeps the service as active even if the main process exits, but does not restart it.
D
Restart=on-failure
This directive tells systemd to restart the service when it exits unexpectedly.

Question 3easymultiple choice

An administrator needs to configure a service to run as a non-root user for security reasons. Which systemd unit file directive accomplishes this?

Trap 1: AmbientCapabilities=CAP_NET_BIND_SERVICE

This grants capabilities, not user identity.

Trap 2: DynamicUser=yes

DynamicUser= creates a transient user, but the actual user is not 'myuser'.

Trap 3: Group=myuser

Group= sets the group, but the user must also be specified.

A
AmbientCapabilities=CAP_NET_BIND_SERVICE
Why wrong: This grants capabilities, not user identity.
B
DynamicUser=yes
Why wrong: DynamicUser= creates a transient user, but the actual user is not 'myuser'.
C
User=myuser
User= specifies the username or UID to run the service.
D
Group=myuser
Why wrong: Group= sets the group, but the user must also be specified.

Question 4hardmultiple choice

A developer reports that a web application's logs are not being written to /var/log/myapp.log. The service runs as user 'myapp' and the log directory /var/log/myapp/ has permissions 755 owned by root. What is the most likely cause?

Trap 1: AppArmor is denying access.

AppArmor is not standard on many distributions and not indicated.

Trap 2: SELinux is blocking the write.

SELinux could be a factor, but without evidence, the permissions issue is more direct.

Trap 3: The service is logging to systemd-journald instead of a file.

The application is configured to write to a file, not journald.

A
AppArmor is denying access.
Why wrong: AppArmor is not standard on many distributions and not indicated.
B
SELinux is blocking the write.
Why wrong: SELinux could be a factor, but without evidence, the permissions issue is more direct.
C
The service is logging to systemd-journald instead of a file.
Why wrong: The application is configured to write to a file, not journald.
D
The service user 'myapp' does not have write permission to the log directory.
The directory is owned by root with 755, so only root can write; myapp needs write permission.

Question 5mediummultiple choice

An administrator wants to ensure that a custom service (myapp.service) starts only after the network is available and the PostgreSQL database service is running. Which systemd unit file directive should be used?

Trap 1: Requires=network.target postgresql.service

Requires= creates a dependency but does not guarantee start order; After= is needed.

Trap 2: Wants=network.target postgresql.service

Wants= is a weaker dependency, but still no ordering.

Trap 3: BindsTo=network.target postgresql.service

BindsTo= binds the service lifecycle to the listed units, but does not specify ordering.

A
Requires=network.target postgresql.service
Why wrong: Requires= creates a dependency but does not guarantee start order; After= is needed.
B
Wants=network.target postgresql.service
Why wrong: Wants= is a weaker dependency, but still no ordering.
C
BindsTo=network.target postgresql.service
Why wrong: BindsTo= binds the service lifecycle to the listed units, but does not specify ordering.
D
After=network.target postgresql.service
After= ensures myapp starts after the listed units are active, combined with Wants= or Requires= for dependency.

Question 6mediummulti select

Which TWO statements are true about systemd service unit files? (Choose two.)

Trap 1: Environment variables can be loaded using EnvFile= directive.

The correct directive is EnvironmentFile=.

Trap 2: The default service type is 'forking'.

The default type is 'simple'.

Trap 3: The [Service] section must appear before the [Unit] section.

The [Unit] section should be first; order does not matter, but convention is [Unit] first.

A
Environment variables can be loaded using EnvFile= directive.
Why wrong: The correct directive is EnvironmentFile=.
B
The default service type is 'forking'.
Why wrong: The default type is 'simple'.
C
The [Service] section is mandatory for a service unit file.
A service unit must have a [Service] section to define the process.
D
The [Install] section is used by systemctl enable to create symlinks.
[Install] defines WantedBy/RequiredBy for enablement.
E
The [Service] section must appear before the [Unit] section.
Why wrong: The [Unit] section should be first; order does not matter, but convention is [Unit] first.

Question 7hardmulti select

Which THREE actions will affect the state of a systemd service that is currently running? (Choose three.)

Trap 1: systemctl disable myapp.service

Disables the service from starting at boot; does not affect current running state.

Trap 2: systemctl daemon-reload

Reloads unit files, but does not modify running services.

A
systemctl kill myapp.service
Sends a signal to the service process.
B
systemctl reload myapp.service
Reloads configuration without restarting.
C
systemctl disable myapp.service
Why wrong: Disables the service from starting at boot; does not affect current running state.
D
systemctl daemon-reload
Why wrong: Reloads unit files, but does not modify running services.
E
systemctl stop myapp.service
Stops the running service.

Question 8mediummultiple choice

An administrator runs 'systemctl status sshd' and sees the output above. The administrator wants sshd to start automatically at boot. Which command should be used?

Exhibit

Refer to the exhibit.

# systemctl status sshd
● sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2025-03-10 14:23:45 UTC; 1h 30min ago
 Main PID: 1234 (sshd)
   CGroup: /system.slice/sshd.service
           └─1234 /usr/sbin/sshd -D

# netstat -tlnp | grep :22
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1234/sshd

Trap 1: systemctl reenable sshd

Not a valid systemctl command; the correct command is 'enable'.

Trap 2: systemctl mask sshd

Masks the service, preventing it from starting.

Trap 3: systemctl start sshd

Starts the service now but does not enable autostart at boot.

A
systemctl reenable sshd
Why wrong: Not a valid systemctl command; the correct command is 'enable'.
B
systemctl mask sshd
Why wrong: Masks the service, preventing it from starting.
C
systemctl start sshd
Why wrong: Starts the service now but does not enable autostart at boot.
D
systemctl enable sshd
Creates symlinks to enable the service to start at boot.

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Question 9hardmultiple choice

A system administrator is configuring a custom systemd service that runs a Python script. The script logs output to stdout. The administrator wants to ensure that the service restarts automatically if it crashes, but only after a 10-second delay. Which directive should be added to the [Service] section of the unit file?

Trap 1: Restart=on-success RestartSec=10

Restarts on successful exit, not on failure.

Trap 2: Restart=always RestartSec=10

Restarts always, even on successful exit, which may not be desired.

Trap 3: RestartSec=10

Sets the delay but does not enable restarting on failure.

A
Restart=on-success RestartSec=10
Why wrong: Restarts on successful exit, not on failure.
B
Restart=on-failure RestartSec=10
Restarts the service only when it exits with a non-zero exit code or is terminated by a signal, with a 10-second delay.
C
Restart=always RestartSec=10
Why wrong: Restarts always, even on successful exit, which may not be desired.
D
RestartSec=10
Why wrong: Sets the delay but does not enable restarting on failure.

Question 10easymultiple choice

A Linux administrator needs to temporarily stop a service named 'httpd' without disabling it from starting automatically on subsequent boots. Which command should be used?

Trap 1: systemctl mask httpd

Masks the service, preventing it from starting.

Trap 2: systemctl disable httpd

Disables the service from starting at boot.

Trap 3: systemctl kill httpd

Sends a signal to the service's processes; does not perform a clean stop.

A
systemctl stop httpd
Stops the service immediately without changing its enable status.
B
systemctl mask httpd
Why wrong: Masks the service, preventing it from starting.
C
systemctl disable httpd
Why wrong: Disables the service from starting at boot.
D
systemctl kill httpd
Why wrong: Sends a signal to the service's processes; does not perform a clean stop.

Question 11easymultiple choice

A system administrator needs to ensure the Apache httpd service starts automatically on system boot. Which command should they use?

Trap 1: systemctl start httpd

systemctl start only starts the service immediately, does not enable boot start.

Trap 2: systemctl disable httpd

systemctl disable removes symlinks, preventing boot start.

Trap 3: systemctl reload httpd

systemctl reload reloads configuration without changing enable status.

A
systemctl enable httpd
systemctl enable creates symlinks for automatic start at boot.
B
systemctl start httpd
Why wrong: systemctl start only starts the service immediately, does not enable boot start.
C
systemctl disable httpd
Why wrong: systemctl disable removes symlinks, preventing boot start.
D
systemctl reload httpd
Why wrong: systemctl reload reloads configuration without changing enable status.

Question 12mediummulti select

Which TWO commands can be used to check the status of the sshd service on a system using systemd?

Trap 1: systemctl list-units --type=service

Lists all services, not specific to sshd.

Trap 2: systemctl is-enabled sshd

Checks if enabled at boot, not current status.

Trap 3: systemctl cat sshd

Displays unit file content, not status.

A
systemctl list-units --type=service
Why wrong: Lists all services, not specific to sshd.
B
systemctl is-active sshd
Returns active/inactive/failed status.
C
systemctl is-enabled sshd
Why wrong: Checks if enabled at boot, not current status.
D
systemctl cat sshd
Why wrong: Displays unit file content, not status.
E
systemctl status sshd
Shows detailed status including active state.

Question 13hardmultiple choice

A company runs a critical web application on a Linux server. The application is managed by a systemd service called 'myapp.service'. Recently, after a scheduled maintenance reboot, the service failed to start automatically. The administrator manually started it with 'systemctl start myapp' and it ran fine. The unit file is located at /etc/systemd/system/myapp.service and contains: [Unit] Description=MyApp After=network.target [Service] ExecStart=/usr/local/bin/myapp Restart=on-failure [Install] WantedBy=multi-user.target. The administrator wants to ensure the service starts automatically after future reboots. However, after running 'systemctl enable myapp', the service still didn't start after the next reboot. What is the most likely cause?

Trap 1: The 'systemctl enable' command only creates symlinks; a separate…

Enable is for boot start, not immediate start; but the service should start at boot.

Trap 2: The 'systemctl enable' command was not run as root.

Even if not root, it would have given an error; but the command succeeded as stated.

Trap 3: The unit file has a syntax error that prevents systemd from parsing…

If there were a syntax error, manual start would also fail.

A
The 'systemctl enable' command only creates symlinks; a separate 'systemctl start' must be run after enable.
Why wrong: Enable is for boot start, not immediate start; but the service should start at boot.
B
The service depends on a target that is not reached before the service starts, and 'Restart=on-failure' does not retry the start if the condition is not met.
With After=network.target, the service may start before network is fully ready; on-failure only restarts if the service exits with non-zero, but if the start fails due to a condition (e.g., network not ready), the service may not be restarted. Using 'Restart=always' or 'RestartSec' can help.
C
The 'systemctl enable' command was not run as root.
Why wrong: Even if not root, it would have given an error; but the command succeeded as stated.
D
The unit file has a syntax error that prevents systemd from parsing it.
Why wrong: If there were a syntax error, manual start would also fail.

Question 14mediumdrag order

Order the steps to create a new partition on a disk using fdisk.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 15mediummatching

Match each Linux process signal to its numeric value.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Question 16easymultiple choice

Which command enables a service to start automatically at boot in a systemd-based system?

Trap 1: systemctl set-default service

Not a valid systemctl command.

Trap 2: systemctl daemon-reload

Reloads systemd configuration, does not enable.

Trap 3: systemctl start service

Starts the service now but not at boot.

A
systemctl enable service
Enables the service to start at boot.
B
systemctl set-default service
Why wrong: Not a valid systemctl command.
C
systemctl daemon-reload
Why wrong: Reloads systemd configuration, does not enable.
D
systemctl start service
Why wrong: Starts the service now but not at boot.

Question 17mediummultiple choice

A custom systemd service unit file has been created but the service fails to start with 'Exec format error'. What is the most likely cause?

Trap 1: The unit file has incorrect permissions

Permissions on the unit file do not affect execution format.

Trap 2: The user does not have permission to start the service

Permission errors show 'permission denied', not exec format.

Trap 3: The service is disabled

Disabling affects boot start, not execution.

A
The unit file has incorrect permissions
Why wrong: Permissions on the unit file do not affect execution format.
B
The user does not have permission to start the service
Why wrong: Permission errors show 'permission denied', not exec format.
C
The service is disabled
Why wrong: Disabling affects boot start, not execution.
D
The ExecStart command path is incorrect or missing shebang
An invalid executable or missing interpreter causes exec format error.

Question 18hardmultiple choice

An administrator configures a systemd service with Restart=on-failure and RestartSec=10. What happens if the service exits with a non-zero exit code?

Trap 1: It restarts immediately

RestartSec introduces a delay.

Trap 2: It retries infinitely regardless of exit code

on-failure only triggers on failure, not success.

Trap 3: It does not restart

on-failure restarts on exit code != 0.

A
It restarts immediately
Why wrong: RestartSec introduces a delay.
B
It retries infinitely regardless of exit code
Why wrong: on-failure only triggers on failure, not success.
C
It does not restart
Why wrong: on-failure restarts on exit code != 0.
D
It waits 10 seconds before restarting
RestartSec defines the delay between restart attempts.

Question 19easymultiple choice

To check the details of a failed systemd service unit, including the last log entries, which command is most appropriate?

Trap 1: systemctl list-units --failed

Lists failed units but does not show logs.

Trap 2: systemctl is-failed service

Only returns exit status, no logs.

Trap 3: systemctl show service

Shows properties, not recent logs.

A
systemctl status service
Shows current state and last log lines.
B
systemctl list-units --failed
Why wrong: Lists failed units but does not show logs.
C
systemctl is-failed service
Why wrong: Only returns exit status, no logs.
D
systemctl show service
Why wrong: Shows properties, not recent logs.

Question 20mediummultiple choice

A service is configured to run as a specific user. Which directive in the [Service] section sets the user?

Trap 1: RunAs

Not a valid systemd directive.

Trap 2: Account

Not a valid systemd directive.

Trap 3: UserID

Not a valid systemd directive.

A
RunAs
Why wrong: Not a valid systemd directive.
B
User
User= specifies the service's user.
C
Account
Why wrong: Not a valid systemd directive.
D
UserID
Why wrong: Not a valid systemd directive.