- A
cosign verify-attestation <image>
Why wrong: Verifies an existing attestation, does not create one.
- B
cosign sign --key <key> <image>
Why wrong: Signs the image but does not create an attestation.
- C
cosign download attestation <image>
Why wrong: Downloads attestation, does not create.
- D
cosign attest --type custom --predicate <file> <image>
Creates a signed attestation with a predicate.
Question 138 of 997
Cosign Attest Command: Create Signed Attestations in CI/CD
This CKS practice question tests your understanding of supply chain security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 security policy requires that all container images must have a signed attestation. Which Cosign command would an admin add to the CI pipeline to create this attestation?
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 attest --type custom --predicate <file> <image>
Option D is correct because the `cosign attest` command is specifically designed to create an in-toto attestation for a container image, attaching a signed predicate (e.g., a SLSA provenance file) that satisfies the policy requirement for a signed attestation. The `--type custom` flag allows specifying a custom predicate type, and `--predicate <file>` provides the attestation payload, which is then signed and stored in the image's OCI manifest as an attached attestation.
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-attestation <image>
Why it's wrong here
Verifies an existing attestation, does not create one.
- ✗
cosign sign --key <key> <image>
Why it's wrong here
Signs the image but does not create an attestation.
- ✗
cosign download attestation <image>
Why it's wrong here
Downloads attestation, does not create.
- ✓
cosign attest --type custom --predicate <file> <image>
Why this is correct
Creates a signed attestation with a predicate.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CNCF CKS exam often tests the distinction between a simple image signature (`cosign sign`) and an attestation (`cosign attest`), where candidates mistakenly choose `cosign sign` because they think signing alone creates an attestation, but attestation requires a structured predicate and the `--type` flag.
Detailed technical explanation
How to think about this question
Cosign attestations are stored as OCI artifacts attached to the image index using the in-toto attestation framework, where the predicate (e.g., SLSA provenance) is wrapped in a DSSE envelope and signed with the specified key. The `cosign attest` command automatically generates the DSSE envelope, signs it, and pushes it to the container registry as a separate layer referenced by the image manifest, allowing policy engines like Kyverno or Ratify to verify the attestation during admission control.
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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All CKS 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 attest --type custom --predicate <file> <image> — Option D is correct because the `cosign attest` command is specifically designed to create an in-toto attestation for a container image, attaching a signed predicate (e.g., a SLSA provenance file) that satisfies the policy requirement for a signed attestation. The `--type custom` flag allows specifying a custom predicate type, and `--predicate <file>` provides the attestation payload, which is then signed and stored in the image's OCI manifest as an attached attestation.
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
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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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