The answer is the built-in Azure Policy definition 'Kubernetes cluster containers should only use allowed images.' This policy is correct because it leverages an Open Policy Agent (OPA) constraint to enforce that every container image deployed in an AKS cluster matches a specified list of allowed registries or image patterns, directly addressing the requirement to restrict container images to an allowed registry. On the Microsoft Cybersecurity Architect exam, this question tests your ability to map Azure Policy definitions to specific security controls within Kubernetes environments—a common trap is confusing this with definitions that audit pod security settings or enforce ingress rules, rather than image source validation. Remember that image authorization is about registry origin, not runtime behavior. A useful memory tip: think of it as the "registry gatekeeper" policy—if the image doesn't come from your approved registry, the OPA constraint blocks the deployment at admission time.
SC-100 Practice Question: Design solutions that align with security best practices and priorities
This SC-100 practice question tests your understanding of design solutions that align with security best practices and priorities. 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.
You are designing a security solution for an Azure Kubernetes Service (AKS) cluster. You need to ensure that only authorized images from a specific container registry can be deployed. Which Azure Policy definition should you use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Kubernetes cluster containers should only use allowed images
Option B is correct because the Azure Policy built-in definition 'Kubernetes cluster containers should only use allowed images' enforces a constraint on the container images deployed in an AKS cluster. This policy uses an Open Policy Agent (OPA) constraint to validate that every container's image reference matches a specified list of allowed registries or image patterns, ensuring only authorized images from a specific container registry can be deployed.
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.
✗
Kubernetes cluster should be accessible only over HTTPS
Why it's wrong here
This is about API server access, not image registry.
✓
Kubernetes cluster containers should only use allowed images
Why this is correct
This built-in policy restricts images to allowed registries.
Related concept
Read the scenario before looking for a memorised answer.
✗
Kubernetes cluster should use internal load balancers
Why it's wrong here
This is about networking, not image source.
✗
Kubernetes cluster should not allow privileged containers
Why it's wrong here
This prevents privileged containers but does not restrict image sources.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse policies that restrict container behavior (like privileged containers) with policies that restrict image sources, leading them to select Option D instead of the correct image-based constraint.
Detailed technical explanation
How to think about this question
Under the hood, the 'allowed images' policy leverages Azure Policy's integration with Gatekeeper v3, which installs OPA constraint templates and constraints on the AKS cluster. The policy parameter 'allowedContainerImagesRegex' allows you to define a regular expression pattern (e.g., 'myregistry.azurecr.io/.*') to match only images from your specific registry. A common subtlety is that this policy does not validate image digests by default, so an attacker could push a malicious tag to the same registry; combining this policy with image signing and admission webhooks like Ratify or Notary provides stronger assurance.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
Design solutions that align with security best practices and priorities — This question tests Design solutions that align with security best practices and priorities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Kubernetes cluster containers should only use allowed images — Option B is correct because the Azure Policy built-in definition 'Kubernetes cluster containers should only use allowed images' enforces a constraint on the container images deployed in an AKS cluster. This policy uses an Open Policy Agent (OPA) constraint to validate that every container's image reference matches a specified list of allowed registries or image patterns, ensuring only authorized images from a specific container registry can be deployed.
What should I do if I get this SC-100 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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