This CKS practice question tests your understanding of cluster setup and hardening. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 developer created a ClusterRoleBinding that grants cluster-admin to a service account. What is the security concern?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It gives the service account full cluster-wide permissions, which is excessive
Option D is correct because granting a service account cluster-admin via a ClusterRoleBinding provides unrestricted, cluster-wide permissions, violating the principle of least privilege. This is a significant security risk as it allows the service account to perform any action on any resource in any namespace, including modifying RBAC rules, secrets, or node configurations. In Kubernetes, service accounts should be bound only to the minimal roles required for their function, typically using RoleBindings scoped to a specific namespace.
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.
✗
Service accounts must use RoleBindings only
Why it's wrong here
Service accounts can use either RoleBindings or ClusterRoleBindings.
✗
ClusterRoleBindings are deprecated
Why it's wrong here
They are not deprecated.
✗
Service accounts cannot use ClusterRoleBindings
Why it's wrong here
Service accounts can be bound to ClusterRoleBindings.
✓
It gives the service account full cluster-wide permissions, which is excessive
Why this is correct
Cluster-admin grants unrestricted access to all resources.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that service accounts are restricted to namespace-scoped bindings, leading candidates to incorrectly choose Option A or C, when in fact Kubernetes allows any subject to be bound to any ClusterRole.
Detailed technical explanation
How to think about this question
Under the hood, a ClusterRoleBinding binds a ClusterRole (which contains rules defined against the RBAC API group) to a subject, granting permissions across all namespaces. The cluster-admin ClusterRole is aggregated from the system:masters group and includes verbs like '*' on all resources, including sensitive subresources like 'tokenreviews' and 'subjectaccessreviews'. In a real-world scenario, a compromised service account with cluster-admin could exfiltrate all secrets, create privileged pods, or delete the entire cluster, making it a critical attack vector.
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: It gives the service account full cluster-wide permissions, which is excessive — Option D is correct because granting a service account cluster-admin via a ClusterRoleBinding provides unrestricted, cluster-wide permissions, violating the principle of least privilege. This is a significant security risk as it allows the service account to perform any action on any resource in any namespace, including modifying RBAC rules, secrets, or node configurations. In Kubernetes, service accounts should be bound only to the minimal roles required for their function, typically using RoleBindings scoped to a specific namespace.
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 →
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.
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.