- A
Enable the AlwaysPullImages admission controller
Why wrong: AlwaysPullImages ensures images are always pulled, but does not change the image reference.
- B
Change the image to 'alpine:latest'
Why wrong: Latest tag is not a SHA digest and would still be rejected.
- C
Add a non-root user to the Dockerfile
Why wrong: Does not affect image pulling based on digest requirement.
- D
Change the image to 'alpine@sha256:...'
Using a SHA digest satisfies the policy requirement for immutable references.
Question 435 of 997
Using SHA Digest to Fix Image Pull Errors in Kubernetes
This CKS practice question tests your understanding of supply chain security. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 user creates a Deployment with image 'alpine:3.18' and the Pod status is 'ErrImagePull'. The admin checks the image policy and sees that only images with SHA digests are allowed. What is the fix?
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
✓
Change the image to 'alpine@sha256:...'
Option D is correct because the cluster policy requires images to be identified by SHA digest rather than tags. Using an image reference like 'alpine@sha256:...' ensures the image is pulled by its immutable digest, bypassing tag-based resolution and satisfying the policy. This is a common supply chain security measure to prevent tag mutability and ensure image integrity.
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.
- ✗
Enable the AlwaysPullImages admission controller
Why it's wrong here
AlwaysPullImages ensures images are always pulled, but does not change the image reference.
- ✗
Change the image to 'alpine:latest'
Why it's wrong here
Latest tag is not a SHA digest and would still be rejected.
- ✗
Add a non-root user to the Dockerfile
Why it's wrong here
Does not affect image pulling based on digest requirement.
- ✓
Change the image to 'alpine@sha256:...'
Why this is correct
Using a SHA digest satisfies the policy requirement for immutable references.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse admission controllers (like AlwaysPullImages) with image reference policies, or assume that changing to a different tag (like 'latest') will bypass the restriction, when in fact the policy explicitly requires a digest-based reference.
Detailed technical explanation
How to think about this question
Image references by digest use the content-addressable storage of the container registry, where the SHA256 hash is computed from the image manifest. This ensures that the exact same image is pulled every time, even if the original tag is moved or deleted. In Kubernetes, the image pull policy is evaluated before the digest check; if the policy rejects tags, the kubelet will fail with ErrImagePull even if the image exists, because the reference does not match the allowed format.
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
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Supply Chain Security practice questions
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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: Change the image to 'alpine@sha256:...' — Option D is correct because the cluster policy requires images to be identified by SHA digest rather than tags. Using an image reference like 'alpine@sha256:...' ensures the image is pulled by its immutable digest, bypassing tag-based resolution and satisfying the policy. This is a common supply chain security measure to prevent tag mutability and ensure image integrity.
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 developer wants to ensure that a pod always uses a specific version of an image that cannot be changed without updating the manifest. Which image reference should be used?
medium- ✓ A.myimage@sha256:abcdef...
- B.myimage:latest
- C.myimage:v1.0
- D.myimage:1.0.0
Why A: Option A (myimage@sha256:abcdef...) uses a digest-based image reference, which pins the image to an immutable content hash. This ensures that the exact same image is always pulled, regardless of tag updates, and any change to the image would require updating the manifest. This aligns with the requirement that the image version cannot be changed without modifying the manifest.
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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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