EX200 Deploy, configure, and maintain systems Practice Question
A system fails to boot and drops into an emergency shell. The administrator suspects a misconfigured /etc/fstab. Which command should be used to determine which filesystem is causing the boot issue?
⚠ Common exam trap
It's easy for candidates to choose `mount -a` (option D) thinking it will show the error, but it only attempts the mount again without providing the specific fstab line or error context, whereas `journalctl -xb -p err` reveals the exact failure from the boot process.
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
✓
journalctl -xb -p err
When a system fails to boot due to a misconfigured /etc/fstab, the emergency shell is entered. The `journalctl -xb -p err` command displays the systemd journal from the current boot (`-b`) with extended information (`-x`) and filters for error-level messages (`-p err`). This will show the exact mount failure and the offending filesystem entry, making it the correct diagnostic tool.
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 status local-fs.target
Why it's wrong here
The systemctl status local-fs.target command reports the current state of the local-fs.target unit, such as whether it is active or failed, but it does not display the underlying cause of a boot problem. It shows only a summary of dependency units and may indicate that a mount unit failed without exposing the specific fstab entry, device node, or mount option that caused the failure. In an emergency shell, you need the actual error messages from the journal, not a high-level status view.
- ✓
journalctl -xb -p err
Why this is correct
Running journalctl -xb -p err reads the persistent journal from the current boot (-b), applies extended explanatory hints (-x) that describe what each message means, and filters to error priority and above (-p err). This will surface kernel driver errors, systemd mount failures, and device not found messages that directly explain why local-fs.target failed. Because the emergency shell runs early in the boot process, the journal still contains the relevant log entries, making this the most reliable diagnostic command.
- ✗
fsck -A
Why it's wrong here
The fsck -A command checks all filesystems listed in /etc/fstab for structural integrity and can repair corruption, but a failure to boot is often caused by an incorrect UUID, missing device, or bad mount option rather than filesystem damage. Running fsck in the emergency shell may be unnecessary or even problematic if filesystems are already mounted, as fsck on a mounted filesystem can cause further corruption. The journal will show the precise reason for mount failure, whereas fsck only addresses a narrow class of issues.
- ✗
mount -a
Why it's wrong here
The mount -a command attempts to mount every filesystem entry in /etc/fstab and will print the error for the first failing entry, but it does not provide the full boot-time context and may silently succeed for already-mounted pseudo filesystems. In an emergency shell, many required kernel devices or service dependencies are not yet set up, so mount -a can produce misleading or incomplete output. The journal, captured by systemd during boot, records the exact ordering of mount attempts and all related kernel messages, which is far more useful than a single immediate attempt.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This EX200 practice question is part of Courseiva's free Red Hat 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 EX200 exam.