CKA Practice Question: Cluster Architecture, Installation & Configuration
This CKA practice question tests your understanding of cluster architecture, installation & configuration. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 Kubernetes cluster is running with a single control plane node. The administrator wants to add a second control plane node for high availability. What is the first step after the new node has been provisioned with the required software?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Run kubeadm join with the --control-plane flag on the new node.
Option B is correct because the first step to add a second control plane node to an existing cluster is to run `kubeadm join` with the `--control-plane` flag on the new node. This command uses the existing control plane's API server to join the new node as a control plane member, automatically distributing certificates and configuring the etcd cluster. The `--control-plane` flag signals kubeadm to set up the additional control plane components (e.g., kube-apiserver, kube-controller-manager, kube-scheduler) and join the etcd cluster as a learner or voting member, depending on the etcd configuration.
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.
✗
Create a bootstrap token on the existing control plane node.
Why it's wrong here
Token creation is part of the process but not the first step; the join command handles it.
✓
Run kubeadm join with the --control-plane flag on the new node.
Why this is correct
kubeadm join with --control-plane is used to add additional control plane nodes.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Run kubeadm init on the new node.
Why it's wrong here
kubeadm init is only for the first control plane node.
✗
Take a snapshot of etcd using etcdctl.
Why it's wrong here
Backup is good practice but not the first step for adding a control plane node.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the process of adding a worker node (which uses `kubeadm join` without `--control-plane`) with adding a control plane node, or mistakenly think that `kubeadm init` or manual etcd backup steps are required first, when in fact the `--control-plane` flag handles the entire control plane join process automatically.
Trap categories for this question
Command / output trap
Token creation is part of the process but not the first step; the join command handles it.
Detailed technical explanation
How to think about this question
When `kubeadm join --control-plane` is executed, it uses the `kubeadm-config` ConfigMap from the existing cluster to retrieve the cluster's CA certificate hash and the bootstrap token for authentication. It then sets up a new API server instance that connects to the existing etcd cluster (either as a learner or directly as a voting member, depending on the etcd version and configuration), and uploads the new node's certificate signing requests (CSRs) to the existing control plane for approval. A subtle behavior is that the new control plane node must have the same Kubernetes version as the existing control plane to ensure compatibility, and the `--certificate-key` flag may be required to securely distribute control plane certificates.
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: Run kubeadm join with the --control-plane flag on the new node. — Option B is correct because the first step to add a second control plane node to an existing cluster is to run `kubeadm join` with the `--control-plane` flag on the new node. This command uses the existing control plane's API server to join the new node as a control plane member, automatically distributing certificates and configuring the etcd cluster. The `--control-plane` flag signals kubeadm to set up the additional control plane components (e.g., kube-apiserver, kube-controller-manager, kube-scheduler) and join the etcd cluster as a learner or voting member, depending on the etcd configuration.
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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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