This EX200 practice question tests your understanding of configure local storage. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A system fails to mount an XFS filesystem at boot. The /etc/fstab entry is: UUID=abc123 /mnt xfs defaults 0 0. Running mount -a shows: 'mount: wrong fs type, bad option, bad superblock on /dev/sdb1'. Which is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The UUID specified in fstab does not match the actual UUID of /dev/sdb1.
The error message 'wrong fs type, bad option, bad superblock' typically indicates that the system cannot identify the filesystem on the device. Since the fstab entry uses UUID=abc123, the most likely cause is that the UUID specified does not match the actual UUID of /dev/sdb1, causing mount to attempt to mount a device that either does not exist or has a different filesystem signature. The mount command first resolves the UUID to a device, and if the UUID is incorrect, it may try to mount the wrong device or fail to find one.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 UUID specified in fstab does not match the actual UUID of /dev/sdb1.
Why this is correct
Mismatched UUID is a common cause; verify with blkid.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The mount point /mnt does not exist.
Why it's wrong here
Missing mount point gives 'mount point does not exist' error.
✗
The kernel does not have XFS support enabled.
Why it's wrong here
XFS is built-in in RHEL; this is unlikely.
✗
The filesystem on /dev/sdb1 is not XFS but ext4.
Why it's wrong here
If that were the case, mount would likely say 'wrong fs type' but not mention superblock.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Red Hat often tests the distinction between a missing mount point (which gives a clear 'No such file or directory' error) and a UUID mismatch (which produces a misleading 'wrong fs type' error), leading candidates to incorrectly suspect kernel support or filesystem type issues.
Detailed technical explanation
How to think about this question
The mount command uses the UUID to locate the block device via /dev/disk/by-uuid/ symlinks. If the UUID in fstab does not match any symlink, mount may fall back to scanning /proc/partitions or /etc/blkid, but if it finds a device with a different UUID, it will attempt to read its superblock and fail with 'wrong fs type' if the superblock signature does not match the expected filesystem. In real-world scenarios, this often occurs after cloning disks or restoring from backups where UUIDs are duplicated or changed, and the fstab is not updated accordingly.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Configure local storage — This question tests Configure local storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The UUID specified in fstab does not match the actual UUID of /dev/sdb1. — The error message 'wrong fs type, bad option, bad superblock' typically indicates that the system cannot identify the filesystem on the device. Since the fstab entry uses UUID=abc123, the most likely cause is that the UUID specified does not match the actual UUID of /dev/sdb1, causing mount to attempt to mount a device that either does not exist or has a different filesystem signature. The mount command first resolves the UUID to a device, and if the UUID is incorrect, it may try to mount the wrong device or fail to find one.
What should I do if I get this EX200 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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