- A
kube-proxy
Why wrong: kube-proxy handles networking rules; its failure does not cause node NotReady.
- B
kube-scheduler
Why wrong: The scheduler runs on the control plane and assigns pods; it does not affect node readiness.
- C
kubelet
The kubelet reports node status; if it's not functioning, the node becomes NotReady.
- D
container runtime (e.g., containerd)
Why wrong: While a container runtime failure can cause kubelet to report NotReady, the kubelet is the component that directly reports status; however, the question asks for the component likely failing, and kubelet is the direct cause. Container runtime failure would be a symptom reported by kubelet. But in practice, if kubelet cannot communicate with runtime, it may also mark node NotReady. However, the typical answer is kubelet. Given options, kubelet is the best choice.
CKA Practice Question: Cluster Architecture, Installation and Configuration
This CKA practice question tests your understanding of cluster architecture, installation and configuration. 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.
You run 'kubectl get nodes' and see that one node is marked as 'NotReady'. Which component is likely failing on that node?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
kubelet
The kubelet is the primary node agent that runs on every node and is responsible for registering the node with the cluster and reporting its status via periodic heartbeats (NodeStatus updates). When a node is marked as 'NotReady', it means the kubelet has failed to send these heartbeats to the control plane (specifically, the node controller) within the --node-monitor-grace-period (default 40s), indicating the kubelet process is likely down, unresponsive, or misconfigured.
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.
- ✗
kube-proxy
Why it's wrong here
kube-proxy handles networking rules; its failure does not cause node NotReady.
- ✗
kube-scheduler
Why it's wrong here
The scheduler runs on the control plane and assigns pods; it does not affect node readiness.
- ✓
kubelet
Why this is correct
The kubelet reports node status; if it's not functioning, the node becomes NotReady.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
container runtime (e.g., containerd)
Why it's wrong here
While a container runtime failure can cause kubelet to report NotReady, the kubelet is the component that directly reports status; however, the question asks for the component likely failing, and kubelet is the direct cause. Container runtime failure would be a symptom reported by kubelet. But in practice, if kubelet cannot communicate with runtime, it may also mark node NotReady. However, the typical answer is kubelet. Given options, kubelet is the best choice.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the container runtime (e.g., containerd) as the direct cause of node unreadiness, but the kubelet is the component that reports the node condition, and a runtime failure would manifest as a kubelet-level error (e.g., 'runtime network not ready') rather than a missing heartbeat.
Trap categories for this question
Real-world vs exam trap
While a container runtime failure can cause kubelet to report NotReady, the kubelet is the component that directly reports status; however, the question asks for the component likely failing, and kubelet is the direct cause. Container runtime failure would be a symptom reported by kubelet. But in practice, if kubelet cannot communicate with runtime, it may also mark node NotReady. However, the typical answer is kubelet. Given options, kubelet is the best choice.
Detailed technical explanation
How to think about this question
The kubelet communicates with the API server to post NodeStatus updates, which include conditions like Ready, DiskPressure, MemoryPressure, etc. The node controller in the cloud-controller-manager or kube-controller-manager checks the last heartbeat timestamp; if it exceeds the --node-monitor-grace-period, it marks the node as NotReady and eventually evicts pods (after --pod-eviction-timeout, default 5m). A real-world scenario is when the kubelet's TLS certificate expires or its --node-ip is misconfigured, causing heartbeat failures even though the kubelet process is running.
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 practitioner preparing for the CKA 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Cluster Architecture, Installation and Configuration — study guide chapter
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FAQ
Questions learners often ask
What does this CKA question test?
Cluster Architecture, Installation and Configuration — This question tests Cluster Architecture, Installation and Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: kubelet — The kubelet is the primary node agent that runs on every node and is responsible for registering the node with the cluster and reporting its status via periodic heartbeats (NodeStatus updates). When a node is marked as 'NotReady', it means the kubelet has failed to send these heartbeats to the control plane (specifically, the node controller) within the --node-monitor-grace-period (default 40s), indicating the kubelet process is likely down, unresponsive, or misconfigured.
What should I do if I get this CKA 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 2026
This CKA 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 CKA exam.
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