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.
A DevOps team is tasked with upgrading a Kubernetes cluster from version 1.21 to 1.22. They want to minimize downtime and follow best practices. Which approach should they take?
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.
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Upgrade the control plane from 1.21 to 1.22 first, then upgrade worker nodes
Option C is correct because the Kubernetes upgrade process mandates upgrading the control plane first, as it is the authoritative source for cluster state and API operations. Worker nodes can then be upgraded to match the control plane version, ensuring compatibility and minimizing downtime by allowing workloads to continue running during the node upgrade phase.
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.
✗
Upgrade worker nodes first, then the control plane
Why it's wrong here
Control plane must be upgraded before worker nodes.
✗
Upgrade etcd to 1.22 first, then the API server
Why it's wrong here
etcd is upgraded as part of control plane upgrade.
✓
Upgrade the control plane from 1.21 to 1.22 first, then upgrade worker nodes
Why this is correct
Component upgrades must follow version skew policy; control plane first.
Clue confirmation
The clue words "best", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Drain all nodes, then upgrade all components to 1.22 at once
Why it's wrong here
Draining is good but upgrading all at once may cause downtime.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume upgrading worker nodes first is safer to avoid control plane downtime, but Kubernetes requires the control plane to be upgraded first to maintain version skew compatibility and cluster stability.
Detailed technical explanation
How to think about this question
The Kubernetes version skew policy (documented in the official Kubernetes documentation) allows worker nodes to be up to two minor versions behind the control plane, but the control plane must always be at the highest version. During a minor version upgrade, the kube-apiserver is upgraded first, followed by the controller-manager and scheduler, then etcd (if needed), and finally worker nodes via kubelet and kube-proxy upgrades. In real-world scenarios, upgrading the control plane first allows the cluster to continue serving API requests while nodes are upgraded one by one (or in batches) to avoid workload disruption.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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: Upgrade the control plane from 1.21 to 1.22 first, then upgrade worker nodes — Option C is correct because the Kubernetes upgrade process mandates upgrading the control plane first, as it is the authoritative source for cluster state and API operations. Worker nodes can then be upgraded to match the control plane version, ensuring compatibility and minimizing downtime by allowing workloads to continue running during the node upgrade phase.
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", "minimum / minimize". 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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