This LFCS practice question tests your understanding of storage management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An administrator needs to encrypt a block device (/dev/sdc) using LUKS. Which command creates an encrypted LUKS container on the device?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
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.
cryptsetup luksOpen /dev/sdc encrypted_device
Why wrong: Opens an existing LUKS container, does not create one.
cryptsetup luksFormat /dev/sdc
Initializes the LUKS container.
openssl enc -aes-256-cbc -in /dev/sdc -out /dev/sdc.enc
Why wrong: OpenSSL encrypts file content, not for block device encryption.
dm-crypt create encrypted /dev/sdc
Why wrong: Legacy method, not the standard LUKS approach.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
cryptsetup luksFormat /dev/sdc
Option B is correct because `cryptsetup luksFormat /dev/sdc` initializes the block device with a LUKS header, setting up an encrypted container that can later be opened with a passphrase or key file. This is the standard command for creating a new LUKS partition, as it writes the LUKS metadata and prepares the device for encryption.
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.
cryptsetup luksOpen /dev/sdc encrypted_device
Why it's wrong here
Opens an existing LUKS container, does not create one.
cryptsetup luksFormat /dev/sdc
Why this is correct
Initializes the LUKS container.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
openssl enc -aes-256-cbc -in /dev/sdc -out /dev/sdc.enc
Why it's wrong here
OpenSSL encrypts file content, not for block device encryption.
dm-crypt create encrypted /dev/sdc
Why it's wrong here
Legacy method, not the standard LUKS approach.
Common exam traps
The trap here is that candidates confuse `luksFormat` (which creates the container) with `luksOpen` (which opens/maps it), or they think a generic encryption tool like `openssl enc` can replace LUKS for block device encryption.
Detailed technical explanation
LUKS (Linux Unified Key Setup) stores encryption metadata in a header at the beginning of the device, including multiple key slots that can hold passphrases or key files. When you run `cryptsetup luksFormat`, it writes this header and initializes the device with a random master key, which is then encrypted by each key slot. A real-world scenario: if you accidentally run `luksFormat` on a device with existing data, the LUKS header overwrites the first few megabytes, making data recovery extremely difficult without a backup of the old header.
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
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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: cryptsetup luksFormat /dev/sdc — Option B is correct because `cryptsetup luksFormat /dev/sdc` initializes the block device with a LUKS header, setting up an encrypted container that can later be opened with a passphrase or key file. This is the standard command for creating a new LUKS partition, as it writes the LUKS metadata and prepares the device for encryption.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 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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