- A
MutatingAdmissionWebhook
Why wrong: MutatingAdmissionWebhook can mutate objects, but it is not specifically designed for image policy. The ImagePolicyWebhook is the dedicated controller for this.
- B
ValidatingAdmissionPolicy
Why wrong: ValidatingAdmissionPolicy is a declarative validation mechanism, but it does not natively integrate with image scanning services. ImagePolicyWebhook is designed for this purpose.
- C
ImagePolicyWebhook
ImagePolicyWebhook is the correct built-in admission controller that can be configured to check images against external scanning services before allowing pod creation.
- D
PodSecurity
Why wrong: PodSecurity enforces Pod Security Standards, not image scanning policies.
Question 79 of 997
ImagePolicyWebhook Admission Controller for Image Scanning
This CKS practice question tests your understanding of supply chain security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 team wants to ensure that all container images in a cluster are scanned for critical CVEs before they are run. They decide to use an admission controller. Which Kubernetes built-in admission controller should they configure?
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
✓
ImagePolicyWebhook
The ImagePolicyWebhook admission controller is the correct choice because it allows an external webhook to validate container images against a policy (e.g., scanning for critical CVEs) before they are admitted into the cluster. It intercepts Pod creation requests and queries an external service to decide whether the image is allowed, making it ideal for enforcing image security scanning at admission time.
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.
- ✗
MutatingAdmissionWebhook
Why it's wrong here
MutatingAdmissionWebhook can mutate objects, but it is not specifically designed for image policy. The ImagePolicyWebhook is the dedicated controller for this.
- ✗
ValidatingAdmissionPolicy
Why it's wrong here
ValidatingAdmissionPolicy is a declarative validation mechanism, but it does not natively integrate with image scanning services. ImagePolicyWebhook is designed for this purpose.
- ✓
ImagePolicyWebhook
Why this is correct
ImagePolicyWebhook is the correct built-in admission controller that can be configured to check images against external scanning services before allowing pod creation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
PodSecurity
Why it's wrong here
PodSecurity enforces Pod Security Standards, not image scanning policies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CKS exam often tests the distinction between admission controllers that enforce security contexts (PodSecurity) versus those that integrate with external scanning services (ImagePolicyWebhook), leading candidates to mistakenly choose PodSecurity because it sounds security-related.
Detailed technical explanation
How to think about this question
The ImagePolicyWebhook works by configuring an `ImagePolicyWebhook` admission plugin in the kube-apiserver, which sends an HTTP POST request to an external webhook endpoint with details about the image (e.g., registry, tag). The webhook must return an `allowed` or `denied` response based on its own scanning logic, and the kube-apiserver enforces this decision before the Pod is persisted. In real-world scenarios, this is often paired with tools like Portieris or OPA Gatekeeper to enforce image trust policies, but the built-in controller itself only provides the webhook integration point.
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.
- →
Supply Chain Security — study guide chapter
Learn the concepts, then practise the questions
- →
Supply Chain Security practice questions
Targeted practice on this topic area only
- →
All CKS questions
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- →
Certified Kubernetes Security Specialist CKS study guide
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CKS practice test guide
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FAQ
Questions learners often ask
What does this CKS question test?
Supply Chain Security — This question tests Supply Chain Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ImagePolicyWebhook — The ImagePolicyWebhook admission controller is the correct choice because it allows an external webhook to validate container images against a policy (e.g., scanning for critical CVEs) before they are admitted into the cluster. It intercepts Pod creation requests and queries an external service to decide whether the image is allowed, making it ideal for enforcing image security scanning at admission time.
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.
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 →
Same concept, more angles
2 more ways this is tested on CKS
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are tasked with ensuring that all container images in your cluster are scanned for vulnerabilities before being deployed. You have set up Trivy in your CI/CD pipeline and want to enforce that only images with no critical vulnerabilities are allowed. Which admission controller should you configure to reject pods using non-compliant images?
medium- ✓ A.ImagePolicyWebhook
- B.ValidatingAdmissionWebhook
- C.PodSecurityPolicy (PSP)
- D.ResourceQuota
Why A: The ImagePolicyWebhook admission controller is specifically designed to evaluate container images against an external policy backend (e.g., Trivy) before they are admitted into the cluster. It intercepts pod creation requests, sends the image reference to an external webhook for validation, and rejects pods whose images contain critical vulnerabilities. This makes it the correct choice for enforcing image vulnerability policies at admission time.
Variation 2. You need to enforce that all images deployed in the cluster are signed by a trusted key. Which Kubernetes admission control mechanism would you use?
medium- A.ResourceQuota
- B.NetworkPolicy
- C.PodSecurityPolicy
- ✓ D.ImagePolicyWebhook
Why D: The ImagePolicyWebhook admission controller is specifically designed to enforce that container images are signed by a trusted key. It intercepts Pod creation requests and validates the image signatures against a configured webhook endpoint, rejecting unsigned or untrusted images. This directly addresses the requirement for supply chain security by ensuring only cryptographically verified images are deployed.
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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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