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.
An administrator wants to secure etcd communication. Which of the following is required?
Set --etcd-servers to use HTTPS
Why wrong: This is a kube-apiserver flag to connect to etcd, but it does not secure etcd itself.
Use SSH tunneling between etcd members
Why wrong: SSH is not used for etcd member communication.
Enable TLS with client certificate authentication
etcd can be configured to require TLS client certificates for all connections.
Enable etcd RBAC
Why wrong: etcd RBAC is for access control, not transport security.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Enable TLS with client certificate authentication
Option C is correct because etcd, as a distributed key-value store, requires TLS encryption with mutual authentication (client certificates) to secure communication between the API server and etcd, as well as between etcd peers. The `--etcd-servers` flag in kube-apiserver must point to HTTPS endpoints, and `--etcd-certfile` and `--etcd-keyfile` enable client certificate authentication, ensuring that only authenticated clients can access etcd data.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Set --etcd-servers to use HTTPS
Why it's wrong here
This is a kube-apiserver flag to connect to etcd, but it does not secure etcd itself.
Use SSH tunneling between etcd members
Why it's wrong here
SSH is not used for etcd member communication.
Enable TLS with client certificate authentication
Why this is correct
etcd can be configured to require TLS client certificates for all connections.
Related concept
Read the scenario before looking for a memorised answer.
Enable etcd RBAC
Why it's wrong here
etcd RBAC is for access control, not transport security.
Common exam traps
The trap here is that candidates often assume HTTPS alone (Option A) is sufficient for securing etcd, overlooking the requirement for mutual TLS authentication with client certificates to prevent unauthorized clients from connecting to etcd.
Detailed technical explanation
Under the hood, etcd uses gRPC with TLS for secure communication; the `--peer-client-cert-auth` and `--client-cert-auth` flags enable mutual TLS (mTLS), where both the server and client present certificates signed by a trusted CA. In a real-world scenario, misconfiguring certificate rotation or using self-signed certificates without proper CA trust can cause cluster outages, as the API server will fail to authenticate with etcd. The `etcdctl` command with `--cacert`, `--cert`, and `--key` flags is used to test mTLS connectivity.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
The correct answer is: Enable TLS with client certificate authentication — Option C is correct because etcd, as a distributed key-value store, requires TLS encryption with mutual authentication (client certificates) to secure communication between the API server and etcd, as well as between etcd peers. The `--etcd-servers` flag in kube-apiserver must point to HTTPS endpoints, and `--etcd-certfile` and `--etcd-keyfile` enable client certificate authentication, ensuring that only authenticated clients can access etcd data.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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