This CKS practice question tests your understanding of cluster setup. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 team needs to set up a highly available Kubernetes control plane across three availability zones. What is the minimum number of etcd members required to achieve fault tolerance against one zone failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
5
Why wrong: 5 members tolerate up to 2 failures, but minimum required is 3.
1
Why wrong: 1 member cannot tolerate any failure.
3
3 members tolerate one member failure, maintaining majority.
7
Why wrong: 7 members tolerate up to 3 failures, but minimum required is 3.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
3
For a highly available Kubernetes control plane across three availability zones, the etcd cluster must tolerate the loss of one entire zone. With three etcd members, one per zone, the cluster requires a majority (2) to form quorum. If one zone fails, the remaining two members still constitute a majority, ensuring continued operation. This matches the minimum odd number greater than one that provides fault tolerance against a single failure.
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.
5
Why it's wrong here
5 members tolerate up to 2 failures, but minimum required is 3.
1
Why it's wrong here
1 member cannot tolerate any failure.
3
Why this is correct
3 members tolerate one member failure, maintaining majority.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
7
Why it's wrong here
7 members tolerate up to 3 failures, but minimum required is 3.
Common exam traps
CNCF often tests the misconception that you need an even number of etcd members for high availability, but the Raft consensus algorithm requires an odd number to avoid split-brain scenarios, and the minimum for fault tolerance against one failure is three, not five or seven.
Detailed technical explanation
Etcd uses the Raft consensus algorithm, which requires a majority (n/2 + 1) of members to agree on any state change. With three members, the majority is 2, so losing one member still allows quorum. In a multi-zone setup, distributing etcd members across zones ensures that a zone failure does not take down more than one member, preserving the majority. Real-world deployments often use three or five members depending on the number of zones and desired resilience, but three is the minimum for single-failure tolerance.
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 — This question tests Cluster Setup — Read the scenario before looking for a memorised answer..
The correct answer is: 3 — For a highly available Kubernetes control plane across three availability zones, the etcd cluster must tolerate the loss of one entire zone. With three etcd members, one per zone, the cluster requires a majority (2) to form quorum. If one zone fails, the remaining two members still constitute a majority, ensuring continued operation. This matches the minimum odd number greater than one that provides fault tolerance against a single failure.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 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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