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.
During a 'kubeadm init', the administrator sees the message 'Your Kubernetes control-plane has been initialized successfully!' but the 'kubectl get nodes' shows the control plane node as 'NotReady'. What is the most likely missing step?
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
✓
Install a CNI plugin such as Calico or Flannel.
The 'NotReady' status indicates that the kubelet on the control plane node is running but cannot report readiness because the node's network is not configured. A CNI plugin (e.g., Calico, Flannel, Weave) must be installed to set up the pod network, which is required for the kubelet to register the node as 'Ready'. Without a CNI plugin, the node's network conditions remain unmet, and the control plane cannot function properly.
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.
✗
Generate a join token for worker nodes.
Why it's wrong here
Join tokens are for adding nodes, not making the control plane ready.
✓
Install a CNI plugin such as Calico or Flannel.
Why this is correct
Without a CNI plugin, node condition stays NotReady.
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.
✗
Copy the kubeconfig to the user's home directory.
Why it's wrong here
kubeconfig allows kubectl to communicate with the cluster, but does not affect node readiness.
✗
Check that the kubelet is running on the control plane node.
Why it's wrong here
kubelet is running; it would show NotReady if network plugin missing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume 'kubeadm init' success means the cluster is fully functional, but they overlook the mandatory post-init step of installing a CNI plugin to make the node 'Ready'.
Trap categories for this question
Command / output trap
kubelet is running; it would show NotReady if network plugin missing.
Detailed technical explanation
How to think about this question
The kubelet on the control plane node reports node conditions based on the status of the container runtime and network plugin. The CNI plugin implements the Kubernetes networking model (RFC 1918, pod-to-pod communication) by configuring interfaces and routes on each node. Without a CNI plugin, the node's 'NetworkReady' condition remains false, and the kubelet sets the node status to 'NotReady'. Common CNI plugins like Calico use BGP for routing, while Flannel uses VXLAN encapsulation.
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: Install a CNI plugin such as Calico or Flannel. — The 'NotReady' status indicates that the kubelet on the control plane node is running but cannot report readiness because the node's network is not configured. A CNI plugin (e.g., Calico, Flannel, Weave) must be installed to set up the pod network, which is required for the kubelet to register the node as 'Ready'. Without a CNI plugin, the node's network conditions remain unmet, and the control plane cannot function properly.
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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Question Discussion
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