easyMultiple ChoiceObjective-mapped
XK0-006 Practice Question: That a Linux workstation fails to boot and…
A user reports that a Linux workstation fails to boot and displays 'Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)'. Which of the following is the most likely cause?
⚠ Common exam trap
Test-takers frequently confuse a boot loader issue (which prevents kernel loading) with a kernel command line misconfiguration (which allows the kernel to load but fail to mount root), leading them to incorrectly select Option 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
✓
The root filesystem device is incorrectly specified in the kernel command line.
The error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates that the kernel cannot locate the root filesystem device. The most likely cause is that the root filesystem device is incorrectly specified in the kernel command line (e.g., via a bootloader parameter like root=), preventing the kernel from finding the correct block device to mount as root.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A filesystem listed in /etc/fstab has errors.
Why it's wrong here
/etc/fstab is read after root is mounted, so it cannot cause this boot-time error.
- ✗
A memory module is faulty.
Why it's wrong here
Faulty memory typically causes random crashes or bit errors, not a specific VFS error.
- ✗
The boot loader is missing or corrupted.
Why it's wrong here
A missing boot loader would not proceed to kernel panic; it would show a different error.
- ✓
The root filesystem device is incorrectly specified in the kernel command line.
Why this is correct
The error 'unable to mount root fs' often means the root= parameter points to a nonexistent or wrong device.
Go deeper
Related to this question
Learn chapter
Linux Fundamentals and History
Key term
Mount
Mounting is the process of making a file system or storage device accessible to a computer's operating system by attaching it to a specific directory in the existing directory tree.
Key term
Linux
Linux is an open-source operating system that manages computer hardware and software, widely used in servers, desktops, and embedded systems.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 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 XK0-006 exam.