EX200 Deploy, configure, and maintain systems Practice Question
A system fails to boot because of a corrupted fstab file. The administrator boots into rescue mode from a RHEL installation ISO. Which command should be run first to mount the root filesystem read-write?
⚠ Common exam trap
Test-takers frequently confuse the rescue mode mount point (/mnt/sysimage) with the emergency mode mount point (/sysroot) or attempt to use chroot before mounting, leading them to select options B or C.
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
✓
mount /dev/mapper/rhel-root /mnt/sysimage
In rescue mode, the root filesystem is not mounted by default. The first step is to mount the logical volume containing the root filesystem (e.g., /dev/mapper/rhel-root) to a temporary mount point like /mnt/sysimage so that you can access and repair the corrupted /etc/fstab file. Option A correctly uses the mount command with the device and mount point, which is the standard procedure for RHEL rescue environments.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
mount /dev/mapper/rhel-root /mnt/sysimage
Why this is correct
When you enter RHEL rescue mode, the installer mounts the installed system's root logical volume at the /mnt/sysimage directory. This command explicitly mounts the LVM logical volume /dev/mapper/rhel-root to that expected mount point, making the filesystem contents visible so you can later chroot and repair /etc/fstab. Without this mount, the repair tools cannot access the system's configuration files.
- ✗
mount -o rw,remount /sysroot
Why it's wrong here
/sysroot is a mount point used only inside the initramfs during early boot; it is not the rescue environment's target directory, which is /mnt/sysimage. Additionally, remounting with -o remount requires the filesystem to already be mounted, but /sysroot is typically not mounted in rescue mode. So this command either fails or operates on the wrong location, leaving the corrupt fstab inaccessible.
- ✗
chroot /mnt/sysimage
Why it's wrong here
The chroot command changes the apparent root directory for the current process, but it does not mount any filesystem; the target directory must already contain a valid Linux root with /bin/bash and other executables. If you run chroot /mnt/sysimage before mounting the root logical volume, the /mnt/sysimage directory is empty, so chroot fails with an error like "chroot: failed to run command '/bin/bash': No such file or directory". Mounting must always precede chroot.
- ✗
systemctl rescue
Why it's wrong here
systemctl rescue switches the running system into rescue mode, which is a minimal single-user target, but it relies on the already-mounted root filesystem of the current boot. It does not automatically mount the root filesystem from the hard disk in a recovery environment; in fact, if fstab is corrupted, systemctl rescue may not even boot properly. For fixing a broken fstab, you need to boot from rescue media and mount the disk, not just invoke systemctl rescue.
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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.