This CKAD practice question tests your understanding of application deployment. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 are using Kustomize. Your kustomization.yaml file specifies a base and an overlay. You run: kubectl apply -k overlays/production. What happens?
It errors because -k expects a directory with kustomization.yaml.
Why wrong: The overlays/production directory likely contains a kustomization.yaml.
It applies the base resources only.
Why wrong: Kustomize merges base and overlay.
It applies the merged result of base and overlay.
Kustomize combines them and kubectl apply creates/updates the resources.
It applies the overlay resources only.
Why wrong: Kustomize merges both.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
It applies the merged result of base and overlay.
Option C is correct because when you run `kubectl apply -k overlays/production`, Kustomize reads the `kustomization.yaml` in the specified directory, which references a base and an overlay. It then performs a strategic merge patch of the overlay's customizations (e.g., patches, namePrefix, commonLabels) onto the base resources, producing a single set of manifests that are applied to the cluster. This is the core purpose of Kustomize: to compose and customize resources without templating.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
It errors because -k expects a directory with kustomization.yaml.
Why it's wrong here
The overlays/production directory likely contains a kustomization.yaml.
It applies the base resources only.
Why it's wrong here
Kustomize merges base and overlay.
It applies the merged result of base and overlay.
Why this is correct
Kustomize combines them and kubectl apply creates/updates the resources.
Related concept
Read the scenario before looking for a memorised answer.
It applies the overlay resources only.
Why it's wrong here
Kustomize merges both.
Common exam traps
The trap here is that candidates might think `-k` applies only the contents of the specified directory (like `-f` does), but Kustomize always resolves the full overlay chain, including the base, so the result is a merged output, not just the overlay's files.
Detailed technical explanation
Under the hood, Kustomize uses a three-step process: first, it loads the base resources; second, it applies the overlay's transformers (e.g., patches, namePrefix, commonLabels, images) to those resources; third, it outputs the final YAML to `kubectl`. A subtle behavior is that if the overlay does not specify a `resources` field that includes the base, Kustomize will still include the base because the overlay's `bases` field (or `resources` in newer versions) explicitly references it. In real-world scenarios, this allows teams to maintain a single base for multiple environments (dev, staging, production) and apply environment-specific patches without duplicating manifests.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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FAQ
Application Deployment — This question tests Application Deployment — Read the scenario before looking for a memorised answer..
The correct answer is: It applies the merged result of base and overlay. — Option C is correct because when you run `kubectl apply -k overlays/production`, Kustomize reads the `kustomization.yaml` in the specified directory, which references a base and an overlay. It then performs a strategic merge patch of the overlay's customizations (e.g., patches, namePrefix, commonLabels) onto the base resources, producing a single set of manifests that are applied to the cluster. This is the core purpose of Kustomize: to compose and customize resources without templating.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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