LFCS User and Group Management Practice Question
A user 'dlee' reports that they cannot run 'sudo' commands despite being in the 'wheel' group. The /etc/sudoers file contains the line '%wheel ALL=(ALL) ALL'. What is the most likely cause?
⚠ Common exam trap
The trap here is assuming that group changes apply immediately; they require a new login session.
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 has not logged out and back in after being added to the 'wheel' group.
The most common reason a user cannot use sudo after being added to a group is that the group membership change has not taken effect in their current session. Linux processes inherit group memberships at login, so a new login is required. After logging out and back in, the user's session will include the 'wheel' group, and sudo will grant access according to the sudoers rule.
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 user has not logged out and back in after being added to the 'wheel' group.
Why this is correct
Group membership changes do not apply to existing sessions. If 'dlee' was added to 'wheel' while logged in, the current session still has the old group set. Logging out and back in refreshes the group memberships, allowing sudo to recognize the new group. This is a common oversight.
- ✗
The user's primary group is not 'wheel'.
Why it's wrong here
The sudoers line uses %wheel, which matches the supplementary group 'wheel'. The primary group does not need to be 'wheel'. As long as 'dlee' is a member of the 'wheel' group (supplementary), sudo should work. This is not the likely cause.
- ✗
The 'wheel' group does not exist on the system.
Why it's wrong here
If the 'wheel' group did not exist, the sudoers line would have no effect, but the user would not be in it either. The scenario states the user is in the 'wheel' group, so the group exists. This is not the likely cause.
- ✗
The sudoers file must be edited with visudo, otherwise changes are ignored.
Why it's wrong here
Editing with visudo is recommended for syntax checking, but sudo reads the file regardless of how it was edited. If the file is syntactically correct, sudo will honor it. The method of editing is not the cause of the problem here.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Linux Foundation exam blueprint
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.