- A
Configure ImagePolicyWebhook to require signatures
ImagePolicyWebhook can reject unsigned images.
- B
Set imagePullPolicy: Always
Why wrong: This does not verify signatures.
- C
Run 'cosign verify' manually before every deployment
Why wrong: Manual verification does not enforce the policy cluster-wide.
- D
Use Kyverno policy to verify image signatures
Kyverno can enforce signature verification.
- E
Use NodeRestriction admission controller
Why wrong: NodeRestriction limits node self-updates, not image signatures.
Question 568 of 997
Enforcing Signed Images in Kubernetes: ImagePolicyWebhook & Kyverno Methods
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.
Which TWO of the following are valid methods to ensure only signed images are deployed in a Kubernetes cluster?
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
✓
Configure ImagePolicyWebhook to require signatures
Option A is correct because the ImagePolicyWebhook admission controller can be configured to reject pods that reference images without valid signatures. It works by sending an admission review request to an external webhook service (e.g., using Cosign or Notary) that validates the image signature before allowing the pod to be created. This enforces signature verification at admission time, preventing unsigned images from running in the cluster.
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.
- ✓
Configure ImagePolicyWebhook to require signatures
Why this is correct
ImagePolicyWebhook can reject unsigned images.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set imagePullPolicy: Always
Why it's wrong here
This does not verify signatures.
- ✗
Run 'cosign verify' manually before every deployment
Why it's wrong here
Manual verification does not enforce the policy cluster-wide.
- ✓
Use Kyverno policy to verify image signatures
Why this is correct
Kyverno can enforce signature verification.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use NodeRestriction admission controller
Why it's wrong here
NodeRestriction limits node self-updates, not image signatures.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF CKS often tests the distinction between admission control mechanisms and runtime or manual verification; the trap here is that candidates may think manual verification (Option C) or pull policies (Option B) are sufficient for cluster-wide enforcement, when in fact only admission controllers or policy engines that intercept pod creation can guarantee that only signed images are deployed.
Detailed technical explanation
How to think about this question
The ImagePolicyWebhook admission controller integrates with an external service (e.g., a Cosign-based verifier) via a kubeconfig-defined webhook URL. The webhook receives an ImageReview object containing the image reference and returns an admission decision based on signature validation. In real-world scenarios, combining ImagePolicyWebhook with a policy engine like Kyverno (Option D) provides layered defense: Kyverno can enforce signature verification using its built-in 'verifyImages' rule, which leverages Cosign to check signatures and attestations before admission, and can also block images from untrusted 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 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
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: Configure ImagePolicyWebhook to require signatures — Option A is correct because the ImagePolicyWebhook admission controller can be configured to reject pods that reference images without valid signatures. It works by sending an admission review request to an external webhook service (e.g., using Cosign or Notary) that validates the image signature before allowing the pod to be created. This enforces signature verification at admission time, preventing unsigned images from running in the cluster.
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
1 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. A security team wants to ensure that only signed images are deployed in the cluster. They have set up an ImagePolicyWebhook admission controller. After configuring the webhook, they notice that pods with unsigned images are still being created. What is the most likely cause?
medium- A.The ImagePolicyWebhook is failing open due to a misconfigured failure policy
- B.The container runtime does not support image signing
- C.The images are signed but the signature is invalid
- ✓ D.The ImagePolicyWebhook is not enabled in the kube-apiserver configuration
Why D: Option D is correct because the ImagePolicyWebhook admission controller must be explicitly enabled in the kube-apiserver configuration via the `--enable-admission-plugins=ImagePolicyWebhook` flag. If it is not enabled, the kube-apiserver will not invoke the webhook at all, allowing unsigned images to be deployed regardless of the webhook's configuration.
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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