- A
cosign verify --key mykey.pub myimage
This verifies the image signature using the public key.
- B
cosign sign --key mykey.pub myimage
Why wrong: This signs the image, not verifies.
- C
cosign download myimage
Why wrong: This downloads signatures, but does not verify.
- D
cosign attest --predicate mypredicate myimage
Why wrong: This creates an attestation, not verify.
Question 780 of 997
Using cosign verify to Validate Container Image Signatures
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.
An administrator wants to verify that an image was signed by a specific key before deploying. Which Cosign command should be used?
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
✓
cosign verify --key mykey.pub myimage
The `cosign verify` command is used to verify the signature of a container image against a public key. By specifying `--key mykey.pub`, the administrator confirms that the image was signed with the corresponding private key before it can be deployed, ensuring supply chain 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.
- ✓
cosign verify --key mykey.pub myimage
Why this is correct
This verifies the image signature using the public key.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
cosign sign --key mykey.pub myimage
Why it's wrong here
This signs the image, not verifies.
- ✗
cosign download myimage
Why it's wrong here
This downloads signatures, but does not verify.
- ✗
cosign attest --predicate mypredicate myimage
Why it's wrong here
This creates an attestation, not verify.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between signing (`cosign sign`) and verifying (`cosign verify`), expecting candidates to know that `verify` is the correct command for checking an image's signature before deployment, not `sign` or `attest`.
Detailed technical explanation
How to think about this question
Cosign uses public-key cryptography where the image digest is signed with a private key, and the signature is stored in an OCI-compliant registry as a separate tag (e.g., `sha256-<digest>.sig`). The `cosign verify` command fetches the signature, computes the image digest, and checks it against the public key using ECDSA-P256 or RSA algorithms. In a real-world CI/CD pipeline, this verification step can be enforced via admission controllers like Kyverno or OPA Gatekeeper to block unsigned images from being deployed.
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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Certified Kubernetes Security Specialist CKS study 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: cosign verify --key mykey.pub myimage — The `cosign verify` command is used to verify the signature of a container image against a public key. By specifying `--key mykey.pub`, the administrator confirms that the image was signed with the corresponding private key before it can be deployed, ensuring supply chain 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.
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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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