This CKS practice question tests your understanding of cluster setup and hardening. 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 ClusterRoleBinding grants cluster-admin to a service account in the 'kube-system' namespace. What is the best way to audit this for least privilege?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Review the permissions granted by cluster-admin and create a custom Role with only necessary permissions, then bind it.
Option D is correct because the cluster-admin ClusterRole grants superuser access across all namespaces, which violates the principle of least privilege. The best practice is to review the specific permissions required by the service account, create a custom Role with only those necessary permissions, and bind it via a RoleBinding or ClusterRoleBinding scoped appropriately. This minimizes the attack surface and aligns with Kubernetes RBAC hardening guidelines.
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 'kubectl auth can-i --list' to check the service account's permissions.
Why it's wrong here
This checks permissions but does not create a least-privilege binding.
✗
Delete the ClusterRoleBinding immediately.
Why it's wrong here
This could break functionality without understanding the impact.
✗
Run 'kubectl get clusterrolebindings' to list all bindings.
Why it's wrong here
This lists bindings but does not analyze them for least privilege.
✓
Review the permissions granted by cluster-admin and create a custom Role with only necessary permissions, then bind it.
Why this is correct
This follows the least privilege principle by scoping permissions to only what is needed.
Clue confirmation
The clue words "best", "least" 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 may think simply listing or checking permissions (Options A or C) is sufficient for auditing, when the core requirement is to reduce permissions to the minimum necessary, which involves creating a custom Role.
Detailed technical explanation
How to think about this question
Under the hood, the cluster-admin ClusterRole aggregates all Kubernetes API verbs and resources via the 'system:master' group and the 'kubernetes-admin' user, effectively granting unrestricted access. When auditing, you should use 'kubectl describe clusterrolebinding <name>' to see the subjects and then 'kubectl describe clusterrole cluster-admin' to understand the full scope of permissions. A real-world scenario is a CI/CD pipeline service account that only needs to create pods and services in a single namespace, but is mistakenly bound to cluster-admin, allowing it to delete nodes or secrets cluster-wide.
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Review the permissions granted by cluster-admin and create a custom Role with only necessary permissions, then bind it. — Option D is correct because the cluster-admin ClusterRole grants superuser access across all namespaces, which violates the principle of least privilege. The best practice is to review the specific permissions required by the service account, create a custom Role with only those necessary permissions, and bind it via a RoleBinding or ClusterRoleBinding scoped appropriately. This minimizes the attack surface and aligns with Kubernetes RBAC hardening guidelines.
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: "best", "least". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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