- A
A constraint template that checks 'spec.containers[*].image' contains 'trusted-registry.io' and a constraint that denies if it does.
Why wrong: This would deny images that contain the string, effectively blocking the trusted registry.
- B
A constraint template that allows all images and a constraint that audits violations.
Why wrong: This does not enforce the requirement to only allow images from the trusted registry.
- C
A constraint template that checks 'spec.containers[*].image' starts with 'trusted-registry.io/' and a constraint that denies if it does not.
This correctly validates that every container image originates from the trusted registry.
- D
A constraint template that checks 'spec.containers[*].image' equals 'trusted-registry.io' and a constraint that denies if it does not.
Why wrong: Images are full URLs, not just the registry name. The check should match the prefix.
OPA Gatekeeper Trusted Registry Constraint
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 security engineer wants to enforce that all images in the cluster must come from a trusted registry 'trusted-registry.io'. They are using OPA/Gatekeeper. Which constraint template and constraint combination would achieve this?
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
A constraint template that checks 'spec.containers[*].image' starts with 'trusted-registry.io/' and a constraint that denies if it does not.
Option C is correct because the constraint template must enforce that container images originate from the trusted registry by checking that the image string starts with 'trusted-registry.io/'. This ensures that only images from that specific registry are allowed, and the constraint denies any pod that does not meet this condition. OPA/Gatekeeper uses Rego policies to evaluate the image field and reject non-compliant resources during admission control.
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.
- ✗
A constraint template that checks 'spec.containers[*].image' contains 'trusted-registry.io' and a constraint that denies if it does.
Why it's wrong here
This would deny images that contain the string, effectively blocking the trusted registry.
- ✗
A constraint template that allows all images and a constraint that audits violations.
Why it's wrong here
This does not enforce the requirement to only allow images from the trusted registry.
- ✓
A constraint template that checks 'spec.containers[*].image' starts with 'trusted-registry.io/' and a constraint that denies if it does not.
Why this is correct
This correctly validates that every container image originates from the trusted registry.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A constraint template that checks 'spec.containers[*].image' equals 'trusted-registry.io' and a constraint that denies if it does not.
Why it's wrong here
Images are full URLs, not just the registry name. The check should match the prefix.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CKS exam often tests the difference between 'contains' and 'startswith' in Rego policies, where candidates mistakenly choose 'contains' thinking it is sufficient, but it fails to prevent images from untrusted registries that include the trusted string in their path.
Detailed technical explanation
How to think about this question
Under the hood, OPA/Gatekeeper evaluates Rego rules against the AdmissionReview request. The constraint template defines a Rego rule that uses `startswith` to match the image prefix, ensuring the registry domain is exactly matched. This approach prevents bypasses via subdomain tricks or path manipulation, as the image must begin with the trusted registry's URL followed by a slash. In real-world scenarios, this pattern is critical for enforcing image provenance in multi-tenant clusters where supply chain attacks often exploit registry confusion.
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
- →
All CKS questions
997 questions across all exam domains
- →
Certified Kubernetes Security Specialist CKS study guide
Full concept coverage aligned to exam objectives
- →
CKS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related CKS practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Monitoring Logging and Runtime Security practice questions
Practise CKS questions linked to Monitoring Logging and Runtime Security.
Cluster Setup and Hardening practice questions
Practise CKS questions linked to Cluster Setup and Hardening.
System Hardening practice questions
Practise CKS questions linked to System Hardening.
Minimize Microservice Vulnerabilities practice questions
Practise CKS questions linked to Minimize Microservice Vulnerabilities.
Supply Chain Security practice questions
Practise CKS questions linked to Supply Chain Security.
Monitoring, Logging and Runtime Security practice questions
Practise CKS questions linked to Monitoring, Logging and Runtime Security.
Cluster Setup practice questions
Practise CKS questions linked to Cluster Setup.
Cluster Hardening practice questions
Practise CKS questions linked to Cluster Hardening.
CKS fundamentals practice questions
Practise CKS questions linked to CKS fundamentals.
CKS scenario practice questions
Practise CKS questions linked to CKS scenario.
CKS troubleshooting practice questions
Practise CKS questions linked to CKS troubleshooting.
Practice this exam
Start a free CKS practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: A constraint template that checks 'spec.containers[*].image' starts with 'trusted-registry.io/' and a constraint that denies if it does not. — Option C is correct because the constraint template must enforce that container images originate from the trusted registry by checking that the image string starts with 'trusted-registry.io/'. This ensures that only images from that specific registry are allowed, and the constraint denies any pod that does not meet this condition. OPA/Gatekeeper uses Rego policies to evaluate the image field and reject non-compliant resources during admission control.
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 →
Keep practising
More CKS practice questions
- Which flag is used to restrict the kubelet's ability to modify node status and pods?
- A Falco rule has priority `WARNING` and output: `Sensitive file opened (user=%user.name command=%proc.cmdline file=%fd.n…
- Falco detects a shell being opened inside a container. Which Falco rule field is used to specify the syscall condition f…
- A security audit reveals that a ServiceAccount named 'monitor' has a ClusterRoleBinding to the cluster-admin role. What…
- Match each Kubernetes security component to its description.
- Match each Kubernetes certificate type to its usage.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.