- A
Use the image digest like 'myapp@sha256:abc123'
Digests are immutable and guarantee the exact image content.
- B
Use a tag like 'v1.0-20231001' with a date
Why wrong: This is still a tag that can be overwritten, though less likely. Digest is the most reliable.
- C
Use the tag 'v1.0' in the image field
Why wrong: Tags can be overwritten; they are mutable.
- D
Pin the image using a 'latest' tag
Why wrong: The 'latest' tag is mutable and can change.
Question 971 of 997
Guaranteeing Image Immutability with SHA Digest References
This CKS practice question tests your understanding of supply chain security. 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.
A developer wants to ensure the container image used in a Deployment is immutable. Which approach BEST guarantees that the exact same image is used every time, preventing tag mutation?
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
✓
Use the image digest like 'myapp@sha256:abc123'
Using the image digest (e.g., `myapp@sha256:abc123`) guarantees immutability because the digest is a cryptographic hash of the image manifest. Unlike tags, which can be reassigned to different images, the digest uniquely identifies a specific image version, ensuring the exact same image is pulled every time regardless of tag changes.
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.
- ✓
Use the image digest like 'myapp@sha256:abc123'
Why this is correct
Digests are immutable and guarantee the exact image content.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a tag like 'v1.0-20231001' with a date
Why it's wrong here
This is still a tag that can be overwritten, though less likely. Digest is the most reliable.
- ✗
Use the tag 'v1.0' in the image field
Why it's wrong here
Tags can be overwritten; they are mutable.
- ✗
Pin the image using a 'latest' tag
Why it's wrong here
The 'latest' tag is mutable and can change.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CNCF CKS exam often tests the misconception that tags with dates or version numbers are immutable, but the trap is that any tag can be reassigned; only the digest provides a cryptographic guarantee of immutability.
Detailed technical explanation
How to think about this question
Image digests are computed from the image manifest using SHA-256 (or SHA-512) and are stored in the container registry as a content-addressable identifier. When you reference an image by digest, the container runtime (e.g., containerd) verifies the digest matches the pulled manifest, preventing any tampering or tag mutation. In real-world scenarios, CI/CD pipelines often use digests in production deployments to ensure rollbacks use the exact same image, avoiding 'tag drift' where a tag like 'v1.0' silently points to a different image after a rebuild.
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
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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: Use the image digest like 'myapp@sha256:abc123' — Using the image digest (e.g., `myapp@sha256:abc123`) guarantees immutability because the digest is a cryptographic hash of the image manifest. Unlike tags, which can be reassigned to different images, the digest uniquely identifies a specific image version, ensuring the exact same image is pulled every time regardless of tag changes.
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. What is the correct way to specify a container image using a SHA digest instead of a tag for immutable deployments?
medium- A.image: myapp:latest
- B.image: myapp:stable
- ✓ C.image: myapp@sha256:abc123...
- D.image: myapp:1.0.0
Why C: Option C is correct because using the `@sha256:` syntax pins the container image to an immutable content digest, ensuring that every pull returns the exact same image regardless of tag updates. This eliminates the risk of tag mutability, where a tag like `latest` can be overwritten with a different image, breaking supply chain integrity and reproducibility.
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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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