CKS Monitoring Logging and Runtime Security Practice Question
This CKS practice question tests your understanding of monitoring logging and runtime 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 security auditor requires that all container images used in the cluster are scanned for vulnerabilities before deployment. The team uses a private registry with image signing. Which solution enforces that only signed and scanned images are deployed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Cosign to sign images and deploy a webhook that verifies signatures.
Cosign is a tool for signing container images, and deploying a validating webhook (e.g., the cosigned admission controller) enforces that only images with valid signatures are admitted. This directly meets the requirement to deploy only signed and scanned images, as the webhook verifies the signature before the pod is created.
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 Cosign to sign images and deploy a webhook that verifies signatures.
Why this is correct
Cosign admission controller can enforce signature verification at pod creation.
Related concept
Read the scenario before looking for a memorised answer.
✗
Run Trivy in a CronJob to scan images and update a ConfigMap with allowed images.
Why it's wrong here
ConfigMap approach is not real-time and can be bypassed.
✗
Use OPA Gatekeeper to verify that the image comes from the private registry.
Why it's wrong here
Registry source does not guarantee scanning or signing.
✗
Enable Binary Authorization on the cluster to enforce image attestation.
Why it's wrong here
Binary Authorization is a GCP-specific feature, not general Kubernetes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between admission-time enforcement (webhooks) and post-deployment scanning (CronJobs), and the trap here is that candidates confuse scanning with enforcement, or assume Binary Authorization is a generic Kubernetes feature when it is actually GKE-specific.
Detailed technical explanation
How to think about this question
Cosign leverages Sigstore for keyless signing using OIDC identity, and the cosigned webhook performs signature verification against a transparency log (Rekor) or a public key. The webhook intercepts Pod creation via a ValidatingAdmissionWebhook and checks the image's signature in the registry's OCI artifact (e.g., `sha256-<digest>.sig`). In practice, this ensures that even if an attacker pushes a malicious image to the private registry, it will be rejected unless it carries a valid signature from an authorized signer.
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.
Monitoring Logging and Runtime Security — This question tests Monitoring Logging and Runtime Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Cosign to sign images and deploy a webhook that verifies signatures. — Cosign is a tool for signing container images, and deploying a validating webhook (e.g., the cosigned admission controller) enforces that only images with valid signatures are admitted. This directly meets the requirement to deploy only signed and scanned images, as the webhook verifies the signature before the pod is created.
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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Question Discussion
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