EX200 Deploy, configure, and maintain systems Practice Question
A system administrator is troubleshooting a RHEL 9 server that fails to boot and drops into emergency mode. The system console shows an error about mounting /dev/sdb1 on /data. The administrator enters emergency mode, checks /etc/fstab, and sees the line: /dev/sdb1 /data ext4 defaults 0 0. The /data directory exists but /dev/sdb1 is a partition on an external USB drive that was removed. The administrator needs the system to boot normally without the USB drive and plans to fix the mount configuration later. Which course of action should the administrator take?
⚠ Common exam trap
Watch out — candidates often think removing the line or adding nofail is the correct fix, but they overlook that the system is already in emergency mode and the immediate goal is to boot normally with minimal changes, making a simple comment-out the safest and most reversible action.
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
✓
Use a text editor to insert '#' at the beginning of the /dev/sdb1 line in /etc/fstab, then reboot.
Commenting out the /dev/sdb1 line in /etc/fstab with '#' prevents systemd from attempting to mount the missing device during boot, allowing the system to boot normally into multi-user.target. This is a safe, reversible change that does not delete the mount point or alter the filesystem, and it preserves the original configuration for later restoration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Remove the line from /etc/fstab and run systemctl daemon-reload, then reboot.
Why it's wrong here
Although removing the /dev/sdb1 line from /etc/fstab does stop systemd from attempting that mount at boot, running systemctl daemon-reload will not re-read /etc/fstab — the fstab file is processed by systemd-fstab-generator only during boot/daemon-reload for unit generation, but not for fstab content changes in this context. The option incorrectly pairs daemon-reload with a procedure that actually requires a reboot for the fstab change to take effect, making the suggested command sequence inaccurate.
- ✗
Add the nofail option to the fstab line, then reboot.
Why it's wrong here
Adding the nofail mount option only instructs systemd to continue booting even if the mount fails; it does not prevent the mount attempt from being made. The /dev/sdb1 device is still missing, so the mount will still fail (silently if nofail is set), but the requirement is to avoid mounting that device altogether — not merely to ignore the failure and proceed.
- ✗
Delete the /data directory and reboot.
Why it's wrong here
Deleting the /data directory removes only the mount point directory from the filesystem, but the /dev/sdb1 entry remains active in /etc/fstab. Since fstab still lists the device, systemd will still attempt the mount at boot, and the absence of the /data directory will cause the mount operation to fail (or behave unpredictably), so the system will not boot normally as required.
- ✓
Use a text editor to insert '#' at the beginning of the /dev/sdb1 line in /etc/fstab, then reboot.
Why this is correct
Inserting a '#' at the start of the /dev/sdb1 line comments out the entire fstab entry, causing systemd-fstab-generator to skip generating a mount unit for that device. With the entry now inactive, no mount attempt is made at boot, and the system avoids the failure while retaining the rest of the fstab configuration for maintenance or later re-enablement.
Go deeper
Related to this question
About these practice questions
Courseiva writes every EX200 question from scratch — 127 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
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.