KCNA Kubernetes Fundamentals Practice Question
You have a ConfigMap named 'app-config' with key 'database.url'. Which environment variable reference in a Pod spec injects this value correctly?
⚠ Common exam trap
Candidates often confuse `configMapKeyRef` with `configMapRef` (which is used with `envFrom`, not `valueFrom`) or mistakenly use `secretKeyRef` for ConfigMaps, thinking the syntax is interchangeable.
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
✓
env: - name: DATABASE_URL valueFrom: configMapKeyRef: name: app-config key: database.url
It uses the `configMapKeyRef` field under `valueFrom` to reference a specific key (`database.url`) from the ConfigMap named `app-config`. This is the standard Kubernetes syntax for injecting a single key from a ConfigMap as an environment variable into a Pod.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
env: - name: DATABASE_URL valueFrom: configMapKeyRef: name: app-config key: database.url
Why this is correct
This correctly references the key 'database.url' from ConfigMap 'app-config'.
- ✗
env: - name: DATABASE_URL value: "$(APP_CONFIG_DATABASE_URL)"
Why it's wrong here
This is not how ConfigMap values are referenced; the syntax is wrong.
- ✗
env: - name: DATABASE_URL valueFrom: secretKeyRef: name: app-config key: database.url
Why it's wrong here
SecretKeyRef is for Secrets, not ConfigMaps.
- ✗
env: - name: DATABASE_URL valueFrom: configMapRef: name: app-config key: database.url
Why it's wrong here
The correct field is 'configMapKeyRef', not 'configMapRef'.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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