CKA Practice Question: Cluster Architecture, Installation & Configuration
This CKA practice question tests your understanding of cluster architecture, installation & 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.
Exhibit
Refer to the exhibit.
```
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
controlplane Ready master 10d v1.25.0
worker1 Ready <none> 10d v1.25.0
worker2 NotReady <none> 10d v1.25.0
$ kubectl describe node worker2 | grep -i condition
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Thu, 01 Jan 2023 00:00:00 +0000 Thu, 01 Jan 2023 00:00:00 +0000 CalicoIsUp Calico is running on this node
MemoryPressure False Thu, 01 Jan 2023 00:00:00 +0000 Thu, 01 Jan 2023 00:00:00 +0000 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Thu, 01 Jan 2023 00:00:00 +0000 Thu, 01 Jan 2023 00:00:00 +0000 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Thu, 01 Jan 2023 00:00:00 +0000 Thu, 01 Jan 2023 00:00:00 +0000 KubeletHasSufficientPID kubelet has sufficient PID available
Ready Unknown Thu, 01 Jan 2023 00:00:00 +0000 Thu, 01 Jan 2023 00:00:00 +0000 NodeStatusUnknown Kubelet stopped posting node status.
```
Based on the exhibit, what is the most likely cause of the worker2 node being NotReady?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The kubelet on worker2 has stopped reporting to the control plane
The kubelet on worker2 has stopped reporting to the control plane, which is the most likely cause of the node being NotReady. The kubelet is responsible for periodically posting node status updates (including heartbeats) to the API server via the NodeStatus update mechanism. If the kubelet process is down, unresponsive, or cannot communicate with the control plane (e.g., due to network partition or certificate expiry), the node controller marks the node as NotReady after the `node-monitor-grace-period` (default 40 seconds) elapses.
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.
✓
The kubelet on worker2 has stopped reporting to the control plane
Why this is correct
The Ready condition is Unknown with message 'Kubelet stopped posting node status'.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The node has insufficient memory
Why it's wrong here
MemoryPressure is False.
✗
The node is experiencing disk pressure
Why it's wrong here
DiskPressure is False.
✗
The network plugin (Calico) is not running on worker2
Why it's wrong here
The NetworkUnavailable condition is False, meaning Calico is running.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between node conditions (MemoryPressure, DiskPressure) and the overall Ready status; the trap here is that candidates confuse a node being under resource pressure (which still allows it to report Ready) with the node being completely unreachable due to kubelet failure.
Detailed technical explanation
How to think about this question
The node controller in the kube-controller-manager monitors node heartbeats via `Node.Status.Conditions[Type=Ready]`. If no update is received within `node-monitor-grace-period` (default 40s), the node is marked `Unknown`, and after `node-startup-grace-period` (default 1m0s) it transitions to `NotReady`. The kubelet's `--node-status-update-frequency` flag (default 10s) controls how often it posts status. A common real-world scenario is the kubelet crashing due to a misconfigured `kubelet-config.yaml` or expired TLS certificates, causing the node to become NotReady even though the node itself 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKA question in full detail.
Cluster Architecture, Installation & Configuration — This question tests Cluster Architecture, Installation & Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The kubelet on worker2 has stopped reporting to the control plane — The kubelet on worker2 has stopped reporting to the control plane, which is the most likely cause of the node being NotReady. The kubelet is responsible for periodically posting node status updates (including heartbeats) to the API server via the NodeStatus update mechanism. If the kubelet process is down, unresponsive, or cannot communicate with the control plane (e.g., due to network partition or certificate expiry), the node controller marks the node as NotReady after the `node-monitor-grace-period` (default 40 seconds) elapses.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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