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 security audit reveals that a service account in the 'default' namespace has been granted cluster-admin privileges via a ClusterRoleBinding. What is the best mitigation?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the ClusterRoleBinding to use a less privileged role
Option C is correct because the best practice is to apply the principle of least privilege: instead of deleting the service account or disabling its token, you should modify the ClusterRoleBinding to bind the service account to a ClusterRole with only the permissions it actually needs. This retains the service account's functionality while removing excessive cluster-admin privileges, which grant unrestricted access to all cluster resources.
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.
✗
Disable the service account token automount
Why it's wrong here
This prevents the token from being mounted but does not revoke the already granted cluster-admin privileges.
✗
Delete the service account
Why it's wrong here
Deleting the service account may affect workloads that depend on it. Better to remove the excessive permissions.
✓
Modify the ClusterRoleBinding to use a less privileged role
Why this is correct
The best approach is to follow least-privilege: bind the service account to a role with only the necessary permissions.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set --authorization-mode=AlwaysDeny
Why it's wrong here
This would deny all requests and break the cluster. Not a valid mitigation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think disabling the token automount or deleting the service account removes the RBAC permissions, but in reality, the ClusterRoleBinding itself must be updated or deleted to actually revoke the granted privileges.
Detailed technical explanation
How to think about this question
Under the hood, a ClusterRoleBinding binds a subject (user, group, or service account) to a ClusterRole, and the RBAC authorizer evaluates these bindings at request time. Even if the service account token is not automounted, the service account still exists and can be used programmatically (e.g., via kubectl with its token). Deleting the service account leaves the ClusterRoleBinding referencing a UID that no longer exists, which Kubernetes may still treat as valid for audit purposes. The correct approach is to update the binding to reference a least-privilege ClusterRole, such as view or edit, or create a custom role with specific resource permissions.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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: Modify the ClusterRoleBinding to use a less privileged role — Option C is correct because the best practice is to apply the principle of least privilege: instead of deleting the service account or disabling its token, you should modify the ClusterRoleBinding to bind the service account to a ClusterRole with only the permissions it actually needs. This retains the service account's functionality while removing excessive cluster-admin privileges, which grant unrestricted access to all cluster resources.
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". 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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Question Discussion
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