This KCNA practice question tests your understanding of kubernetes fundamentals. 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.
Which THREE of the following are core components of a Kubernetes worker node?
etcd
Why wrong: etcd is a control plane component.
kube-apiserver
Why wrong: API server is a control plane component.
container runtime
Container runtime runs containers.
kube-proxy
Kube-proxy maintains network rules.
kubelet
Kubelet ensures containers run in pods.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
container runtime
Option C is correct because a container runtime is a core component of a Kubernetes worker node. It is responsible for actually running the containers (e.g., containerd, CRI-O) and is required by the kubelet to manage pod lifecycle. Without a container runtime, the kubelet cannot start or stop containers on the node.
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.
etcd
Why it's wrong here
etcd is a control plane component.
kube-apiserver
Why it's wrong here
API server is a control plane component.
container runtime
Why this is correct
Container runtime runs containers.
Related concept
Read the scenario before looking for a memorised answer.
kube-proxy
Why this is correct
Kube-proxy maintains network rules.
Related concept
Read the scenario before looking for a memorised answer.
kubelet
Why this is correct
Kubelet ensures containers run in pods.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse control plane components (etcd, kube-apiserver) with worker node components, especially when they see them listed together in a question about cluster architecture.
Detailed technical explanation
The kubelet on each worker node communicates with the container runtime via the Container Runtime Interface (CRI), which abstracts the runtime implementation (e.g., containerd, CRI-O, or Docker via cri-dockerd). In production, containerd is the most common runtime due to its lightweight design and direct CRI support. A real-world scenario where this matters is when a misconfigured container runtime causes pods to stay in 'ContainerCreating' state, often due to missing runtime endpoints or incompatible CRI versions.
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 KCNA 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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: container runtime — Option C is correct because a container runtime is a core component of a Kubernetes worker node. It is responsible for actually running the containers (e.g., containerd, CRI-O) and is required by the kubelet to manage pod lifecycle. Without a container runtime, the kubelet cannot start or stop containers on the node.
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 KCNA 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 KCNA exam.
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