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 DevOps team uses a CI/CD pipeline to build container images and push them to a private registry. To minimize the risk of supply chain attacks, which of the following is the most effective security control to implement?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Sign all container images using a private key and verify the signature before deployment.
Option D is correct because signing container images with a private key and verifying the signature before deployment ensures image integrity and authenticity, directly mitigating supply chain attacks where an attacker could tamper with images in transit or at rest. This control, often implemented using tools like Notary or Cosign (part of the Sigstore project), provides cryptographic proof that the image was produced by a trusted source and has not been altered. Without signature verification, even a vulnerability-scanned image could be replaced with a malicious one, bypassing other controls.
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.
✗
Scan all images for vulnerabilities using Trivy before pushing to the registry.
Why it's wrong here
Vulnerability scanning detects known CVEs but does not prevent malicious image tampering.
✗
Restrict access to the registry using Kubernetes RBAC and service accounts.
Why it's wrong here
RBAC controls who can push/pull images but does not protect against tampered images.
✗
Implement network policies to restrict traffic to the registry endpoint.
Why it's wrong here
Network policies control traffic flow but do not verify image content.
✓
Sign all container images using a private key and verify the signature before deployment.
Why this is correct
Image signing provides cryptographic assurance of image integrity and origin, a core supply chain security control.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
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 vulnerability scanning (which detects known flaws) with image signing (which ensures integrity and provenance), and mistakenly choose scanning as the primary defense against supply chain attacks, overlooking that a scanned image can still be replaced or tampered with.
Detailed technical explanation
How to think about this question
Container image signing typically uses a public-key infrastructure (PKI) where the image digest is signed with a private key, and the signature is stored in an OCI-compliant registry as a separate tag or in a notation store. Tools like Cosign leverage the Sigstore ecosystem, which includes a transparency log (Rekor) for auditability and Fulcio for short-lived certificates, enabling keyless signing. In a real-world scenario, an attacker who compromises the CI/CD pipeline could push a malicious image with a valid vulnerability scan result, but signature verification would fail because the image digest does not match the signed digest, blocking deployment.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
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: Sign all container images using a private key and verify the signature before deployment. — Option D is correct because signing container images with a private key and verifying the signature before deployment ensures image integrity and authenticity, directly mitigating supply chain attacks where an attacker could tamper with images in transit or at rest. This control, often implemented using tools like Notary or Cosign (part of the Sigstore project), provides cryptographic proof that the image was produced by a trusted source and has not been altered. Without signature verification, even a vulnerability-scanned image could be replaced with a malicious one, bypassing other controls.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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