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XK0-006 Practice Question: A Linux engineer is troubleshooting a server that…

A Linux engineer is troubleshooting a server that fails to boot. The server displays a message indicating 'Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)'. Which TWO actions should the engineer take to resolve this issue? (Choose TWO.)

⚠ Common exam trap

It's easy for candidates to confuse a kernel panic about root filesystem mounting with a bootloader or filesystem corruption issue, leading them to choose GRUB reinstallation (A) or fsck (C) instead of addressing the initramfs or kernel command line.

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

Boot from a rescue disk and rebuild the initramfs with the necessary filesystem modules

The error 'Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate or mount the root filesystem. Option B is correct because rebuilding the initramfs from a rescue disk ensures the necessary filesystem drivers (e.g., ext4, xfs) are included, which may have been missing or corrupted. Option D is correct because the root= parameter in the bootloader configuration (e.g., GRUB) tells the kernel which device/partition to mount as root; a typo or incorrect value (e.g., wrong UUID or device name) will cause this exact panic.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Reinstall GRUB to the Master Boot Record

    Why it's wrong here

    Reinstalling GRUB addresses bootloader issues, not kernel panic due to missing root filesystem.

  • Boot from a rescue disk and rebuild the initramfs with the necessary filesystem modules

    Why this is correct

    Rebuilding initramfs includes required modules for root filesystem access.

  • Run fsck on the root partition to check for filesystem corruption

    Why it's wrong here

    fsck repairs filesystem errors but does not fix missing drivers or wrong root= parameter.

  • Check the kernel command line in the bootloader configuration for the correct root= parameter

    Why this is correct

    Incorrect root= parameter prevents the kernel from finding the root filesystem.

  • Disable SELinux by adding selinux=0 to the kernel command line

    Why it's wrong here

    SELinux does not affect the kernel's ability to mount the root filesystem.

Visual reference

Client Recursive Resolver Root DNS (13 root servers) TLD DNS (.com, .org, …) Authoritative example.com query IP addr answer

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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.