Quick Answer
The answer is `lsblk`. This command lists all block devices that the kernel has detected, including raw disks without any partitions or filesystems, making it the ideal first step when a new disk is not recognized by the kernel. Unlike `fdisk -l` or `parted`, which may fail to display an unpartitioned disk, `lsblk` reads directly from the sysfs filesystem and will show `/dev/sdb` if the kernel has enumerated it, even on a UEFI system with GPT partitioning. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your ability to differentiate between kernel-level detection and higher-level partitioning tools—a common trap is reaching for `fdisk` first, which can be misleading if the disk lacks a partition table. Remember the memory tip: “List before you partition” with `lsblk` to confirm the kernel sees the hardware before you attempt any further configuration.
This LFCS practice question tests your understanding of storage management. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 administrator notices that a new 500GB SSD (/dev/sdb) is not being recognized by the system after installation. The server uses UEFI and GPT partitioning. Which command should the administrator run first to verify that the disk is detected by the kernel?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
fdisk -l /dev/sdb
Why wrong: fdisk -l would work but requires root and is not the first step; lsblk is simpler.
lsblk
lsblk lists all block devices, including /dev/sdb, and does not require root.
cat /proc/cpuinfo
Why wrong: This shows CPU info, not disk detection.
lsusb
Why wrong: lsusb lists USB devices, but /dev/sdb may be SATA/SAS, not USB.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
lsblk
The `lsblk` command lists all block devices recognized by the kernel, including those without a filesystem or partition table. Since the disk is new and not yet partitioned, `lsblk` will show it if the kernel has detected it, making it the correct first diagnostic step.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
fdisk -l /dev/sdb
Why it's wrong here
fdisk -l would work but requires root and is not the first step; lsblk is simpler.
lsblk
Why this is correct
lsblk lists all block devices, including /dev/sdb, and does not require root.
Clue confirmation
The clue words "first", "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
cat /proc/cpuinfo
Why it's wrong here
This shows CPU info, not disk detection.
lsusb
Why it's wrong here
lsusb lists USB devices, but /dev/sdb may be SATA/SAS, not USB.
Common exam traps
The trap here is that candidates often jump to `fdisk -l` as the first command, but it requires the device to already be recognized and may produce misleading errors if the disk is not detected, whereas `lsblk` directly shows kernel-level recognition without needing a partition table.
Trap categories for this question
Command / output trap
This shows CPU info, not disk detection.
Detailed technical explanation
Under the hood, the Linux kernel detects storage devices during boot or via hotplug and creates device nodes under `/dev/` (e.g., `/dev/sdb`). The `lsblk` command reads the sysfs filesystem (`/sys/block/`) to enumerate all block devices, regardless of whether they have a partition table or filesystem. In a UEFI/GPT system, the disk may appear in `lsblk` even without a valid GPT header, allowing the administrator to confirm kernel detection before proceeding with partitioning.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
The correct answer is: lsblk — The `lsblk` command lists all block devices recognized by the kernel, including those without a filesystem or partition table. Since the disk is new and not yet partitioned, `lsblk` will show it if the kernel has detected it, making it the correct first diagnostic step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first", "which command". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.
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