This LFCS practice question tests your understanding of user and group 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.
A Linux administrator wants to restrict user 'alice' to only be able to use the system for non-interactive tasks (e.g., running cron jobs and receiving mail) but not allow her to log in via SSH or console. Which TWO actions would achieve this goal? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set alice's login shell to /sbin/nologin in /etc/passwd.
Options A and B are correct. Setting the shell to /sbin/nologin prevents interactive logins but cron and mail still work because they use /bin/sh independently. Adding to DenyUsers in sshd_config blocks SSH only. Option C does not block SSH key authentication. Option D gives root privileges instead of blocking. Option E blocks cron, which is not desired.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged 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.
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related LFCS questions on access control and AAA configuration.
User and Group Management — This question tests User and Group Management — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Set alice's login shell to /sbin/nologin in /etc/passwd. — Options A and B are correct. Setting the shell to /sbin/nologin prevents interactive logins but cron and mail still work because they use /bin/sh independently. Adding to DenyUsers in sshd_config blocks SSH only. Option C does not block SSH key authentication. Option D gives root privileges instead of blocking. Option E blocks cron, which is not desired.
What should I do if I get this LFCS question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related LFCS questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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Question Discussion
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