- A
PodSecurityPolicy
Why wrong: PSP is deprecated and replaced by OPA Gatekeeper or Pod Security Admission.
- B
ValidatingAdmissionWebhook
Gatekeeper registers a ValidatingWebhookConfiguration to intercept and validate pod requests.
- C
ServiceAccount
Why wrong: This is not an admission controller but a controller managing service accounts.
- D
NodeRestriction
Why wrong: This limits kubelet permissions, not related to OPA.
Question 820 of 997
OPA Gatekeeper and ValidatingAdmissionWebhook
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. 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.
Which Kubernetes admission controller is responsible for mutating and validating pod requests based on policies defined by OPA Gatekeeper?
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
✓
ValidatingAdmissionWebhook
OPA Gatekeeper uses the ValidatingAdmissionWebhook admission controller to intercept pod creation requests and enforce policies defined as ConstraintTemplates and Constraints. This webhook validates requests against Rego policies before they are persisted, rejecting non-compliant pods. The ValidatingAdmissionWebhook is the correct mechanism because Gatekeeper does not mutate requests—it only validates them.
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.
- ✗
PodSecurityPolicy
Why it's wrong here
PSP is deprecated and replaced by OPA Gatekeeper or Pod Security Admission.
- ✓
ValidatingAdmissionWebhook
Why this is correct
Gatekeeper registers a ValidatingWebhookConfiguration to intercept and validate pod requests.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
ServiceAccount
Why it's wrong here
This is not an admission controller but a controller managing service accounts.
- ✗
NodeRestriction
Why it's wrong here
This limits kubelet permissions, not related to OPA.
Common exam traps
Common exam trap: answer the scenario, not the keyword
In the CKS exam, candidates often confuse OPA Gatekeeper with mutating admission webhooks. Gatekeeper uses ValidatingAdmissionWebhook to enforce policies, not MutatingAdmissionWebhook, as it only validates requests and does not mutate them.
Detailed technical explanation
How to think about this question
OPA Gatekeeper operates as a dynamic admission webhook registered via ValidatingWebhookConfiguration, which triggers on CREATE and UPDATE operations for pods. The webhook receives AdmissionReview requests and returns AdmissionResponse with 'allowed: false' if the pod violates a Constraint. Under the hood, Gatekeeper's audit controller also periodically checks existing resources against constraints, generating violations in the status field of Constraint objects.
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: ValidatingAdmissionWebhook — OPA Gatekeeper uses the ValidatingAdmissionWebhook admission controller to intercept pod creation requests and enforce policies defined as ConstraintTemplates and Constraints. This webhook validates requests against Rego policies before they are persisted, rejecting non-compliant pods. The ValidatingAdmissionWebhook is the correct mechanism because Gatekeeper does not mutate requests—it only validates them.
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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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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