EX200 Configure local storage Practice Question
Which single command shows the UUID of a filesystem on /dev/sdb1?
⚠ Common exam trap
Candidates often confuse partition table tools like `fdisk` with filesystem metadata tools, or assume `mount` shows UUIDs by default, when in fact only `blkid` (or `lsblk -f`) directly queries the filesystem superblock for the UUID.
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
✓
blkid /dev/sdb1
The `blkid /dev/sdb1` command queries the libblkid library to read the filesystem metadata directly from the block device, displaying attributes including the UUID (Universally Unique Identifier) stored in the superblock. This is the standard, single-purpose command to retrieve the UUID of a specific partition.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
df -h
Why it's wrong here
df -h reports filesystem disk space utilization for mounted filesystems, showing columns such as size, used, available, use%, and mount point. It never reads or displays filesystem metadata like the UUID from the superblock; it only summarizes current usage statistics. Since /dev/sdb1 might not even be mounted, df cannot be relied upon to reveal the UUID of that device.
- ✗
mount
Why it's wrong here
The mount command with no arguments lists only currently mounted filesystems and their mount points, device names, and filesystem types. Although it may mention /dev/sdb1 if that partition is mounted, its output does not include the UUID assigned to the filesystem. The system maps device names to UUIDs internally in /etc/fstab or via systemd, but plain mount output lacks that detail.
- ✓
blkid /dev/sdb1
Why this is correct
blkid is the util-linux utility that directly reads the superblock of a block device to display its UUID, filesystem type, and label. Running blkid /dev/sdb1 causes it to inspect that specific partition and print the filesystem UUID, making it the only command here that accomplishes the task. This works whether or not /dev/sdb1 is mounted, because blkid queries the raw device metadata.
- ✗
fdisk -l
Why it's wrong here
fdisk -l displays the partition table for a disk, listing entries such as /dev/sdb1 with their start and end sectors and partition type code. It only deals with the partition layout and cannot see inside the filesystem superblock, so it has no access to the filesystem UUID. A partition can exist without any filesystem, and fdisk never inspects filesystem metadata, so it is not a valid way to show the UUID.
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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.