XK0-006 Security Practice Question
A Linux administrator needs to prevent the root user from logging in via SSH. Which directive should be set in /etc/ssh/sshd_config to accomplish this?
⚠ Common exam trap
It's easy for candidates to confuse `PasswordAuthentication no` with blocking root login, not realizing that root could still authenticate via SSH keys or other mechanisms if `PermitRootLogin` is not explicitly set to `no`.
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
✓
PermitRootLogin no
The directive `PermitRootLogin no` in `/etc/ssh/sshd_config` explicitly disallows the root user from authenticating via SSH, regardless of the authentication method used. This is the standard way to block root SSH logins while still allowing other users to connect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
PasswordAuthentication no
Why it's wrong here
This disables password authentication for all users but does not specifically block root.
- ✓
PermitRootLogin no
Why this is correct
This setting prevents root from logging in via SSH.
- ✗
MaxAuthTries 1
Why it's wrong here
This limits authentication attempts but does not block root login.
- ✗
AllowUsers root
Why it's wrong here
This would allow root access, not block it.
Go deeper
Related to this question
Learn chapter
Linux Fundamentals and History
Key term
Linux
Linux is an open-source operating system that manages computer hardware and software, widely used in servers, desktops, and embedded systems.
Key term
SSH
SSH (Secure Shell) is a cryptographic network protocol that provides secure, encrypted communication and remote administration between two devices over an unsecured network.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 practice question is part of Courseiva's free CompTIA 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 XK0-006 exam.