LFCS Essential Commands Practice Question
Network Topology
A user 'dba' tries to login via SSH and fails. Based on the exhibit, what is the most likely cause?
⚠ Common exam trap
Many candidates assume SSH login failures are always due to authentication (password/key) or file permissions, but the LFCS exam frequently tests the subtle point that an invalid login shell causes a successful authentication followed by an immediate session termination, which appears as a login failure.
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 user 'dba' has an invalid login shell.
The exhibit shows that the user 'dba' has an invalid login shell (e.g., /sbin/nologin or /bin/false). When the login shell is set to a non-interactive shell, SSH authentication succeeds but the session immediately closes, preventing the user from logging in. This is a common configuration for system accounts or users who should not have interactive shell access.
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 file /home/dba/file.txt is corrupt.
Why it's wrong here
Unrelated to login.
- ✓
The user 'dba' has an invalid login shell.
Why this is correct
/bin/false prevents login.
- ✗
The user 'dba' is not in the 'docker' group.
Why it's wrong here
Group membership not relevant for SSH login.
- ✗
The home directory /home/dba does not have correct permissions.
Why it's wrong here
Permissions are 755, which is acceptable.
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Related to this question
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.