Quick Answer
The correct sequence is `systemctl stop application; sync; reboot`. This order is critical because `systemctl stop` sends a SIGTERM signal to the application, allowing it to perform a graceful shutdown by closing files and flushing its buffers, which prevents data corruption. The `sync` command then forces any pending disk writes in the kernel’s page cache to complete, ensuring filesystem consistency before the hardware resets. On the CompTIA Linux+ XK0-005 exam, this question tests your understanding of the Linux boot and shutdown process, specifically the difference between a graceful stop and a forced kill. A common trap is choosing `kill -9` or `shutdown -r now` alone, which bypasses the application’s cleanup routines. Remember the mnemonic “Stop, Sync, Start” — always stop the service first, sync the disks, then reboot to avoid data loss.
This XK0-005 practice question tests your understanding of system management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 server running a critical application needs to be rebooted. To ensure the application stops gracefully and data is not corrupted, which sequence of commands should the administrator use?
killall -9 application; reboot
Why wrong: Sends SIGKILL, not graceful.
reboot
Why wrong: Reboots without stopping services gracefully.
systemctl stop application; sync; reboot
Stops service gracefully, syncs disks, then reboots.
umount -a; reboot
Why wrong: Unmounts all filesystems without syncing or stopping services.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
systemctl stop application; sync; reboot
Option C is correct because it first uses systemctl to send a SIGTERM to the application, allowing it to perform a graceful shutdown and flush its data. The sync command then forces any pending disk writes to complete, ensuring filesystem consistency before the reboot. This sequence minimizes the risk of data corruption by giving the application and kernel time to finalize all I/O operations.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
killall -9 application; reboot
Why it's wrong here
Sends SIGKILL, not graceful.
reboot
Why it's wrong here
Reboots without stopping services gracefully.
systemctl stop application; sync; reboot
Why this is correct
Stops service gracefully, syncs disks, then reboots.
Related concept
Read the scenario before looking for a memorised answer.
umount -a; reboot
Why it's wrong here
Unmounts all filesystems without syncing or stopping services.
Common exam traps
CompTIA often tests the misconception that a simple reboot or killall -9 is sufficient for critical applications, but the trap here is that candidates overlook the need for a graceful stop and filesystem sync to prevent data corruption.
Detailed technical explanation
The systemctl stop command sends a SIGTERM (signal 15) to the application's main process, which the application can catch to run cleanup routines like closing database connections and flushing buffers. The sync command triggers the kernel's sync system call, which writes all dirty buffers from the page cache to disk, ensuring that data is physically stored before the reboot. In a real-world scenario, a database server (e.g., MySQL) might take several seconds to commit transactions and release locks; skipping the sync could leave the filesystem journal in an inconsistent state, requiring a lengthy fsck on next boot.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
System Management — This question tests System Management — Read the scenario before looking for a memorised answer..
The correct answer is: systemctl stop application; sync; reboot — Option C is correct because it first uses systemctl to send a SIGTERM to the application, allowing it to perform a graceful shutdown and flush its data. The sync command then forces any pending disk writes to complete, ensuring filesystem consistency before the reboot. This sequence minimizes the risk of data corruption by giving the application and kernel time to finalize all I/O operations.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.
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