CKA Practice Question: Cluster Architecture, Installation and Configuration
You want to upgrade the control plane from v1.28.0 to v1.29.0 using kubeadm. After upgrading kubeadm on the control plane node, which command should you run first?
⚠ Common exam trap
Watch out — candidates often confuse the sequence and jump directly to `kubeadm upgrade apply`, thinking it is the first step, but the CKA exam tests the prerequisite validation step (`kubeadm upgrade plan`) to ensure a safe upgrade process.
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
✓
kubeadm upgrade plan
After upgrading kubeadm on the control plane node, the first command to run is `kubeadm upgrade plan`. This command checks the current cluster version, validates that the upgrade path is supported (e.g., from v1.28.0 to v1.29.0), and displays the available versions to upgrade to, along with any manual steps required. It is a prerequisite to ensure the upgrade is safe before proceeding with `kubeadm upgrade apply`.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
kubeadm upgrade plan
Why this is correct
Running `kubeadm upgrade plan` is the recommended first step when upgrading a Kubernetes control plane. This command analyzes your cluster to check if it can be upgraded, detects the current component versions, and displays the available target versions along with the exact configuration changes that will be applied. It ensures there are no version compatibility blockers before you commit to the actual upgrade process.
- ✗
kubeadm upgrade apply v1.29.0
Why it's wrong here
While `kubeadm upgrade apply` is the actual command used to execute the control plane upgrade to a specific version, running it directly without first executing `kubeadm upgrade plan` is a violation of recommended operational practices. The planning phase is critical to verify the upgrade path, check API compatibility, and ensure the cluster state is healthy. Skipping the plan step can lead to unexpected failures during the live upgrade execution.
- ✗
kubeadm upgrade node
Why it's wrong here
The `kubeadm upgrade node` command is specifically designed to upgrade secondary control plane instances and worker nodes after the primary control plane node has already been successfully upgraded. It does not perform the initial cluster-wide upgrade planning or apply the main control plane configuration changes. Attempting to run this command first on the primary control plane node will fail to initiate the overall cluster upgrade.
- ✗
kubeadm upgrade diff
Why it's wrong here
There is no `diff` subcommand under `kubeadm upgrade` in the standard Kubernetes administration toolset. While tools like `kubectl diff` exist to compare local manifests with live cluster states, `kubeadm` does not offer a native `diff` command to preview upgrade changes. To see the proposed changes and version differences before upgrading, administrators must rely on the output of `kubeadm upgrade plan`.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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