This CKS practice question tests your understanding of cluster setup and hardening. 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.
Which THREE of the following are valid methods to restrict access to etcd in a Kubernetes cluster? (Select THREE)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use TLS certificates for client and server authentication
Option A is correct because etcd supports mutual TLS (mTLS) authentication, where both the client (e.g., kube-apiserver) and the etcd server present TLS certificates to verify each other's identity. This is the standard and recommended method for securing communication between the API server and etcd, as it prevents unauthorized clients from accessing the key-value store and ensures data-in-transit encryption.
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 TLS certificates for client and server authentication
Why this is correct
Mutual TLS ensures only authenticated clients can connect.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable RBAC authorization in etcd
Why this is correct
etcd supports RBAC to restrict access to keys.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use simple username and password authentication
Why it's wrong here
Simple passwords are not recommended; TLS and RBAC provide stronger security.
✗
Put etcd on the same network as the API server without firewall
Why it's wrong here
This does not restrict access; it exposes etcd to potential network threats.
✓
Encrypt etcd data at rest
Why this is correct
Encryption at rest protects data if the storage is compromised.
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 etcd can use simple username/password authentication or that network placement alone is sufficient for security, when in fact TLS mutual authentication and encryption at rest are the required hardening measures.
Detailed technical explanation
How to think about this question
etcd's authentication model is based on TLS mutual authentication, where the `--client-cert-auth` flag must be enabled on the etcd server, and the API server is configured with `--etcd-certfile`, `--etcd-keyfile`, and `--etcd-cafile` to present its certificate. Additionally, etcd supports role-based access control (RBAC) via its own user/role system (enabled with `--auth-token` and `etcdctl user add`), but this is separate from Kubernetes RBAC and is not commonly used in production—TLS client certificates remain the primary access control mechanism.
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: Use TLS certificates for client and server authentication — Option A is correct because etcd supports mutual TLS (mTLS) authentication, where both the client (e.g., kube-apiserver) and the etcd server present TLS certificates to verify each other's identity. This is the standard and recommended method for securing communication between the API server and etcd, as it prevents unauthorized clients from accessing the key-value store and ensures data-in-transit encryption.
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.
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Question Discussion
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