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XK0-006 Practice Question: An administrator is troubleshooting a server that…
An administrator is troubleshooting a server that fails to boot. The system 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
Many candidates confuse a kernel panic at the VFS mount stage with a corrupted kernel image or hardware failure, when the real cause is a misconfigured bootloader parameter that prevents the kernel from finding the root filesystem.
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
✓
Incorrect root= parameter in the kernel command line
The error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate the root filesystem. The 'unknown-block(0,0)' value means the kernel received no valid device number for the root partition, which is almost always caused by an incorrect or missing 'root=' parameter in the kernel command line (e.g., in GRUB). This prevents the kernel from finding the correct block device to mount as '/'.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The init binary is missing
Why it's wrong here
Missing init causes 'kernel panic - not syncing: Attempted to kill init!'.
- ✗
The hard drive has a hardware failure
Why it's wrong here
Hardware failure typically results in different errors such as 'Drive not ready'.
- ✗
The kernel image is corrupted
Why it's wrong here
Corrupted kernel causes decompression errors.
- ✗
The Master Boot Record is damaged
Why it's wrong here
MBR damage prevents GRUB from loading.
- ✓
Incorrect root= parameter in the kernel command line
Why this is correct
The root filesystem cannot be mounted due to wrong root= parameter.
Go deeper
Related to this question
Learn chapter
Navigating the Filesystem
Key term
Kernel
The kernel is the core program of an operating system that manages hardware resources and provides essential services for all other software to run.
Key term
Kernel panic
A kernel panic is a critical system error that occurs when the operating system's core (the kernel) encounters an unrecoverable fault, causing the system to stop all operations and often display an error message or a screen of death.
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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.