- A
ImagePolicyWebhook
ImagePolicyWebhook is an admission controller specifically for image policy validation, often used with image signing.
- B
MutatingAdmissionWebhook
Why wrong: MutatingAdmissionWebhook mutates resources; it is not specifically for image validation.
- C
ValidatingAdmissionWebhook
Why wrong: ValidatingAdmissionWebhook is a generic webhook that can be used for any validation, but ImagePolicyWebhook is specifically designed for image policy.
- D
NodeRestriction
Why wrong: NodeRestriction is for limiting node permissions, not image validation.
Question 932 of 997
Using ImagePolicyWebhook to Validate Image Signatures in Kubernetes
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.
You are tasked with creating a Kubernetes admission controller that validates image signatures before allowing pods to run. Which admission controller should you 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 specifically designed to validate container image signatures against an external policy engine (e.g., OPA, Sigstore) before a pod is admitted. It intercepts pod creation requests and sends the image metadata to a webhook endpoint, which returns an allow/deny decision based on signature verification. This directly addresses the requirement to enforce image signature validation as part of supply chain security.
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.
- ✓
ImagePolicyWebhook
Why this is correct
ImagePolicyWebhook is an admission controller specifically for image policy validation, often used with image signing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
MutatingAdmissionWebhook
Why it's wrong here
MutatingAdmissionWebhook mutates resources; it is not specifically for image validation.
- ✗
ValidatingAdmissionWebhook
Why it's wrong here
ValidatingAdmissionWebhook is a generic webhook that can be used for any validation, but ImagePolicyWebhook is specifically designed for image policy.
- ✗
NodeRestriction
Why it's wrong here
NodeRestriction is for limiting node permissions, not image validation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse ValidatingAdmissionWebhook (a generic validation tool) with ImagePolicyWebhook (the specific controller for image signature validation), but the CKS exam expects you to know the exact admission controller designed for this supply chain security use case.
Detailed technical explanation
How to think about this question
The ImagePolicyWebhook works by configuring a kube-apiserver flag (--admission-control-config-file) pointing to a YAML file that defines the external webhook endpoint and failure policy. Under the hood, it sends an ImageReview object containing the pod's image references to the webhook, which must return an ImageReviewStatus with an allowed boolean. A real-world scenario is integrating with Sigstore's cosign to verify that images are signed by a trusted authority before deployment, preventing supply chain attacks like typosquatting or compromised registries.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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
997 questions across all exam domains
- →
Certified Kubernetes Security Specialist CKS study guide
Full concept coverage aligned to exam objectives
- →
CKS practice test guide
How to use practice tests most effectively before exam day
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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 specifically designed to validate container image signatures against an external policy engine (e.g., OPA, Sigstore) before a pod is admitted. It intercepts pod creation requests and sends the image metadata to a webhook endpoint, which returns an allow/deny decision based on signature verification. This directly addresses the requirement to enforce image signature validation as part of supply chain security.
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. Which admission controller is responsible for validating and modifying images based on an external webhook in Kubernetes?
easy- A.MutatingAdmissionWebhook
- ✓ B.ImagePolicyWebhook
- C.PodSecurity
- D.ValidatingAdmissionWebhook
Why B: The ImagePolicyWebhook admission controller is specifically designed to validate and modify container images by querying an external webhook before admitting a pod. It allows an external service to enforce image policies, such as checking image signatures or blocking untrusted registries, making it the correct answer for this scenario.
Variation 2. Which Kubernetes admission controller ensures that a pod only uses images from a specific registry?
easy- A.NamespaceLifecycle
- ✓ B.ImagePolicyWebhook
- C.PodNodeSelector
- D.AlwaysPullImages
Why B: The ImagePolicyWebhook admission controller allows you to define a webhook that validates container images against a policy, such as restricting them to a specific registry. When a pod is created, Kubernetes sends an admission review to the webhook, which can reject images not from the allowed registry. This is the correct choice because it directly enforces image source policies.
Keep practising
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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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