The answer is to run the container as a non-root user. This is the best practice because containers share the host kernel, so a process running as root inside the container has the same user ID (UID 0) on the host, creating a direct path for privilege escalation if the container is compromised. By enforcing a non-root user, you strip the attacker of inherent superuser capabilities, effectively breaking the chain of escalation at the kernel level. On the CompTIA SecurityX CAS-004 exam, this concept tests your understanding of defense-in-depth for containerized environments, often appearing in scenario-based questions where you must choose between reducing the attack surface and preserving functionality. A common trap is selecting a read-only filesystem, which limits writes but does nothing to restrict the privilege level of the running process. Remember the mnemonic: “No root, no route” — without root, there is no direct route to the host kernel.
CAS-004 Practice Question: Application Environment, Configuration and Security
This CAS-004 practice question tests your understanding of application environment, configuration and security. 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 security analyst discovers that a containerized application is running with root privileges. Which of the following is the best practice to reduce the attack surface?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Run the container as a non-root user
Option B is correct because running as a non-root user limits privilege escalation. Option A (read-only filesystem) helps but does not address root privileges. Option C (disable network) may break functionality. Option D (minimal base image) reduces attack surface but does not directly address privilege level.
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.
✗
Use a minimal base image
Why it's wrong here
A minimal base image reduces attack surface but does not address the root user issue.
✗
Disable network access for the container
Why it's wrong here
Network access may be required for functionality; disabling it arbitrarily is not a best practice.
✓
Run the container as a non-root user
Why this is correct
Running as non-root ensures the container does not have unnecessary privileges, reducing the blast radius of a compromise.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
Use a read-only root filesystem
Why it's wrong here
While good, it does not remove root privileges; a root process could still cause harm.
Common exam traps
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
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 CAS-004 questions on access control and AAA configuration.
Application Environment, Configuration and Security — This question tests Application Environment, Configuration and Security — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Run the container as a non-root user — Option B is correct because running as a non-root user limits privilege escalation. Option A (read-only filesystem) helps but does not address root privileges. Option C (disable network) may break functionality. Option D (minimal base image) reduces attack surface but does not directly address privilege level.
What should I do if I get this CAS-004 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 CAS-004 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This CAS-004 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 CAS-004 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.