CompTIA XK0-005 Practice Test

XK0-005 practice test: what's covered

• Linux+ XK0-005
• Vendor-Neutral Linux Administration

Free XK0-005 sample questions

1. A new admin runs <code>service nginx restart</code> on a RHEL 9 server and the service does restart — but you want them using the modern, canonical tool that does NOT rely on a legacy wrapper. Which command is the BEST replacement?

   • A. systemctl restart nginx
   • B. systemctl reload nginx
   • C. /etc/init.d/nginx restart
   • D. nginx -s restart
   Show answer

   Correct: A. On systemd distros, <code>service</code> is a compatibility wrapper that calls systemctl behind the scenes. The canonical command is <code>systemctl restart nginx</code>. <code>reload</code> only re-reads config without dropping connections — not the same as restart. <code>/etc/init.d/</code> is SysV legacy. <code>nginx -s restart</code> is not a valid nginx signal (valid ones are stop/quit/reload/reopen).

2. You created <code>/etc/systemd/system/backup.service</code> but <code>systemctl start backup</code> says "Unit backup.service not found." What is the FIRST command to run?

   • A. systemctl restart systemd
   • B. systemctl daemon-reload
   • C. systemctl enable backup.service --now
   • D. systemd-tmpfiles --create
   Show answer

   Correct: B. After creating or modifying any unit file in /etc/systemd/system/ you MUST run <code>systemctl daemon-reload</code> so systemd re-reads its unit graph. Without it, the unit is invisible. <code>systemctl restart systemd</code> is dangerous and unnecessary. <code>enable --now</code> would also fail with the same "not found" error until daemon-reload happens.

3. A junior admin sees the output below and asks why the service is not running. What is the correct interpretation? <pre>$ systemctl status nginx ● nginx.service - The nginx HTTP and reverse proxy server Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; preset: disabled) Active: inactive (dead)</pre>

   • A. The service is broken — reinstall nginx
   • B. The service is installed but NOT enabled at boot and NOT currently started. Run <code>systemctl enable --now nginx</code>
   • C. The service has crashed and dumped a core
   • D. The unit file is corrupt
   Show answer

   Correct: B. "Loaded: loaded ... disabled" means the unit file is found and parsed, but it is NOT enabled (no boot-time symlink) and the preset is also disabled. "Active: inactive (dead)" means it is not currently running. <code>systemctl enable --now</code> both enables and starts in one shot.

4. You want a backup job to run every day at 02:00 with a randomised delay and persistent missed-run handling (so it still runs after a reboot if the system was down at 02:00). Which TWO systemd timer features achieve this? (Choose 2)

   • A. OnCalendar=*-*-* 02:00:00
   • B. Persistent=true
   • C. OnBootSec=2h
   • D. RandomizedDelaySec=600
   • E. WantedBy=cron.target
   Show answer

   Correct: A and B. <code>OnCalendar</code> defines the schedule. <code>Persistent=true</code> tracks last-run time on disk and triggers a make-up run on the next boot if the timer was missed (this is exactly what crontab's anacron does, but built into systemd). <code>OnBootSec</code> would be a different trigger (boot-relative). <code>RandomizedDelaySec</code> is useful but not what the question asks for. There is no cron.target — timers depend on timers.target.

5. A systemd service has <code>Restart=on-failure</code> but a buggy app keeps crashing and respawning fast. Which directive PREVENTS systemd from giving up and marking the service as failed after too many restarts in too short a window?

   • A. StartLimitBurst= and StartLimitIntervalSec= (raise the burst threshold or widen the window)
   • B. RestartSec= (just slow each restart down)
   • C. TimeoutStopSec= (give it more time to stop)
   • D. KillMode=process
   Show answer

   Correct: A. systemd has a rate-limit: by default 5 starts in 10 seconds triggers a "start-limit-hit" and the unit is held down. Tune <code>StartLimitBurst</code> (how many) and <code>StartLimitIntervalSec</code> (over what window) in the [Unit] section. <code>RestartSec</code> only delays each retry — it does not change the burst threshold. Raising RestartSec helps but is not the directive that controls the giving-up behaviour.

Last updated: 2026-10-19

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