- A
Set runAsNonRoot to true in securityContext
Ensures the container runs as a non-root user.
- B
Run containers as root inside the container for easier management
Why wrong: Running as root increases security risk.
- C
Set readOnlyRootFilesystem to true in securityContext
Prevents writes to the root filesystem, reducing attack surface.
- D
Mount the docker socket inside the container for debugging
Why wrong: Mounting the docker socket gives the container host-level access and is dangerous.
- E
Use the latest tag for all images
Why wrong: Using latest is not recommended; it can lead to inconsistent versions and security issues.
Question 440 of 997
Securing Container Images and Runtime — Recommended Practices | Certified Kubernetes Security Specialist Explained
This CKS practice question tests your understanding of minimize microservice vulnerabilities. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: runAsNonRoot. 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.
Which TWO of the following are recommended practices for securing container images and runtime?
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
✓
Set runAsNonRoot to true in securityContext
Setting `runAsNonRoot: true` in the securityContext ensures that the container's entrypoint runs with a user ID other than 0 (root), reducing the risk of container escape if an attacker gains code execution. Setting `readOnlyRootFilesystem: true` makes the container's filesystem read-only, preventing attackers from modifying critical system files or binaries. Both are key hardening practices recommended by Kubernetes security best practices.
Key principle: runAsNonRoot
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set runAsNonRoot to true in securityContext
Why this is correct
Ensures the container runs as a non-root user.
Related concept
runAsNonRoot
- ✗
Run containers as root inside the container for easier management
Why it's wrong here
Running as root increases security risk.
- ✓
Set readOnlyRootFilesystem to true in securityContext
Why this is correct
Prevents writes to the root filesystem, reducing attack surface.
Related concept
runAsNonRoot
- ✗
Mount the docker socket inside the container for debugging
Why it's wrong here
Mounting the docker socket gives the container host-level access and is dangerous.
- ✗
Use the latest tag for all images
Why it's wrong here
Using latest is not recommended; it can lead to inconsistent versions and security issues.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common pitfall is thinking that running as root inside a container is safe due to namespace isolation. However, root inside a container still has dangerous capabilities (e.g., CAP_SYS_ADMIN) that can lead to container escape, especially without proper seccomp or AppArmor profiles. This is a critical concept for the CNCF Kubernetes Security Specialist exam.
Detailed technical explanation
How to think about this question
Under the hood, `runAsNonRoot: true` works by setting the container's user ID in the process's user namespace; if the image's default user is root (UID 0), the Pod will fail to start, forcing the image to be built with a non-root user. Setting `readOnlyRootFilesystem: true` mounts the container's root filesystem as read-only, preventing any writes to the container's filesystem layer, which thwarts many common attack vectors like dropping malicious binaries or modifying configuration files at runtime. In a real-world scenario, combining these two settings with a non-root user and an emptyDir volume for writable temporary data creates a robust defense-in-depth posture against container breakout and persistence attacks.
KKey Concepts to Remember
- runAsNonRoot
- readOnlyRootFilesystem
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
runAsNonRoot
Real-world example
How this comes up in practice
A practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. runAsNonRoot Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Review runAsNonRoot, then practise related CKS questions on the same topic to reinforce the concept.
- →
Minimize Microservice Vulnerabilities — study guide chapter
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Minimize Microservice Vulnerabilities practice questions
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — runAsNonRoot.
What is the correct answer to this question?
The correct answer is: Set runAsNonRoot to true in securityContext — Setting `runAsNonRoot: true` in the securityContext ensures that the container's entrypoint runs with a user ID other than 0 (root), reducing the risk of container escape if an attacker gains code execution. Setting `readOnlyRootFilesystem: true` makes the container's filesystem read-only, preventing attackers from modifying critical system files or binaries. Both are key hardening practices recommended by Kubernetes security best practices.
What should I do if I get this CKS question wrong?
Review runAsNonRoot, then practise related CKS questions on the same topic to reinforce the concept.
What is the key concept behind this question?
runAsNonRoot
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Last reviewed: Jul 4, 2026
This CKS practice question is part of Courseiva's free CNCF 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 CKS exam.
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