- A
The administrator forgot to restart the SSH service after locking accounts.
Why wrong: Restarting SSH would not change the behavior; key authentication is still allowed.
- B
The SSH daemon is configured to allow passwordless login for locked accounts.
Why wrong: SSH does not have a specific setting for locked accounts; key authentication bypasses the lock.
- C
The usermod -L command only locks password-based login, not SSH key login.
usermod -L sets an '!' in the password field, which prevents password authentication but not SSH key authentication.
- D
The users have valid SSH keys in their ~/.ssh/authorized_keys, and SSH does not check the account lock status.
Why wrong: While SSH does not check the lock flag, the correct answer is that usermod -L only affects password auth.
LPIC-1 Administrative Tasks Practice Question
This LPIC-1 practice question tests your understanding of administrative tasks. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 company security policy requires that user accounts be disabled after 90 days of inactivity. The system administrator locks user accounts using 'usermod -L username'. However, users with SSH key authentication can still log in. The administrator has verified that the locked flag is set in /etc/shadow. Which of the following is the most likely explanation?
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 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
The usermod -L command only locks password-based login, not SSH key login.
The `usermod -L` command locks a user account by placing a '!' in the password hash field of /etc/shadow, which only prevents authentication via password-based methods (e.g., PAM's pam_unix). SSH key authentication uses the SSH protocol's public-key challenge-response, which is handled by the SSH daemon (sshd) and does not consult the locked password field in /etc/shadow. Therefore, users with valid SSH keys in ~/.ssh/authorized_keys can still log in despite the account being locked.
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 administrator forgot to restart the SSH service after locking accounts.
Why it's wrong here
Restarting SSH would not change the behavior; key authentication is still allowed.
- ✗
The SSH daemon is configured to allow passwordless login for locked accounts.
Why it's wrong here
SSH does not have a specific setting for locked accounts; key authentication bypasses the lock.
- ✓
The usermod -L command only locks password-based login, not SSH key login.
Why this is correct
usermod -L sets an '!' in the password field, which prevents password authentication but not SSH key authentication.
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 users have valid SSH keys in their ~/.ssh/authorized_keys, and SSH does not check the account lock status.
Why it's wrong here
While SSH does not check the lock flag, the correct answer is that usermod -L only affects password auth.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume 'locking' an account with `usermod -L` disables all login methods, but it only affects password-based authentication, not SSH key-based or other non-password mechanisms.
Detailed technical explanation
How to think about this question
Under the hood, `usermod -L` modifies the second field in /etc/shadow by prepending a '!' to the password hash, which causes PAM's pam_unix module to reject any password-based login attempt. However, SSH key authentication uses the SSH protocol's public-key challenge (RFC 4252), which is handled by sshd's own authentication logic (e.g., AuthorizedKeysFile) and does not call pam_unix for password verification. In real-world scenarios, this is a common security gap: administrators relying solely on `usermod -L` to disable accounts may leave SSH key access open, requiring additional steps like removing the user's SSH keys or using `passwd -l` (which also only locks password auth).
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.
- →
Administrative Tasks — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this LPIC-1 question test?
Administrative Tasks — This question tests Administrative Tasks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The usermod -L command only locks password-based login, not SSH key login. — The `usermod -L` command locks a user account by placing a '!' in the password hash field of /etc/shadow, which only prevents authentication via password-based methods (e.g., PAM's pam_unix). SSH key authentication uses the SSH protocol's public-key challenge-response, which is handled by the SSH daemon (sshd) and does not consult the locked password field in /etc/shadow. Therefore, users with valid SSH keys in ~/.ssh/authorized_keys can still log in despite the account being locked.
What should I do if I get this LPIC-1 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.
About these practice questions
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Last reviewed: Jun 25, 2026
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.
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