- A
Create a PodSecurityPolicy that requires runAsNonRoot
Why wrong: PodSecurityPolicy is deprecated in Kubernetes 1.25+ and removed in 1.29. It should not be used for new deployments.
- B
Use OPA/Gatekeeper with a ConstraintTemplate that checks runAsNonRoot is set to true
OPA/Gatekeeper can enforce policies via admission webhooks, and a ConstraintTemplate can validate that all containers have runAsNonRoot: true.
- C
Set runAsNonRoot in the securityContext of each Pod spec manually
Why wrong: This does not enforce the policy cluster-wide; it only applies to specific pods. It is not scalable.
- D
Configure a ValidatingAdmissionPolicy with a CEL rule requiring runAsNonRoot
Why wrong: While ValidatingAdmissionPolicy (beta) could be used, OPA/Gatekeeper is the more mature and commonly used tool for such policies.
Enforcing Non-Root at Cluster Level with OPA Gatekeeper | Certified Kubernetes Security Specialist Explained
This CKS practice question tests your understanding of minimize microservice vulnerabilities. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
You are implementing a policy to ensure all containers in a namespace run as non-root. Which of the following is the most appropriate approach to enforce this at the cluster level?
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
Use OPA/Gatekeeper with a ConstraintTemplate that checks runAsNonRoot is set to true
Option B is correct because OPA/Gatekeeper allows you to enforce custom policies at the cluster level via ConstraintTemplates and Constraints. By creating a ConstraintTemplate that checks `runAsNonRoot: true` in the Pod securityContext, you can ensure all Pods in a namespace (or cluster-wide) run as non-root, without modifying individual Pod specs. This approach is native to Kubernetes admission control and provides a flexible, cluster-wide enforcement mechanism.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a PodSecurityPolicy that requires runAsNonRoot
Why it's wrong here
PodSecurityPolicy is deprecated in Kubernetes 1.25+ and removed in 1.29. It should not be used for new deployments.
- ✓
Use OPA/Gatekeeper with a ConstraintTemplate that checks runAsNonRoot is set to true
Why this is correct
OPA/Gatekeeper can enforce policies via admission webhooks, and a ConstraintTemplate can validate that all containers have runAsNonRoot: true.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set runAsNonRoot in the securityContext of each Pod spec manually
Why it's wrong here
This does not enforce the policy cluster-wide; it only applies to specific pods. It is not scalable.
- ✗
Configure a ValidatingAdmissionPolicy with a CEL rule requiring runAsNonRoot
Why it's wrong here
While ValidatingAdmissionPolicy (beta) could be used, OPA/Gatekeeper is the more mature and commonly used tool for such policies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common pitfall in the CKS exam is assuming that PodSecurityPolicy (PSP) is still a viable cluster-level enforcement mechanism. However, PSP was deprecated in Kubernetes v1.21 and removed in v1.25. The modern approach uses either OPA/Gatekeeper with ConstraintTemplates or Kubernetes Pod Security Standards (PSS) via labels or built-in admission controllers. Candidates often choose PSP out of habit, but it is no longer available in recent clusters.
Detailed technical explanation
How to think about this question
OPA/Gatekeeper works by intercepting admission requests via a mutating or validating webhook. The ConstraintTemplate defines a Rego rule that inspects the Pod spec's `securityContext.runAsNonRoot` field; if it is missing or set to `false`, the admission request is denied. This approach leverages the Open Policy Agent (OPA) engine, which can evaluate complex policies beyond simple field checks, such as requiring `runAsUser: 1000` or disallowing privileged containers, making it ideal for real-world multi-tenant clusters where fine-grained control is needed.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Minimize Microservice Vulnerabilities — study guide chapter
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use OPA/Gatekeeper with a ConstraintTemplate that checks runAsNonRoot is set to true — Option B is correct because OPA/Gatekeeper allows you to enforce custom policies at the cluster level via ConstraintTemplates and Constraints. By creating a ConstraintTemplate that checks `runAsNonRoot: true` in the Pod securityContext, you can ensure all Pods in a namespace (or cluster-wide) run as non-root, without modifying individual Pod specs. This approach is native to Kubernetes admission control and provides a flexible, cluster-wide enforcement mechanism.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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 →
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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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