CKAD Application Design and Build Practice Question
A developer is defining a Pod that uses an init container to prepare a shared volume before the main application container starts. The init container must download configuration files into an emptyDir volume, and the main container must read them. Which TWO statements about this Pod design are correct? (Choose two.)
⚠ Common exam trap
The trap here is assuming init containers can run in parallel with app containers or that readiness probes apply to them, when they must complete before any app container starts.
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
✓
An emptyDir volume declared in the Pod spec can be mounted by both the init container and the main container, allowing files written by the init container to be visible to the main container.
Init containers run sequentially to completion before app containers start, ensuring the shared emptyDir is populated first. Because emptyDir is Pod-scoped and can be mounted by multiple containers, the init container can write files that the main container reads.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
If an init container fails, Kubernetes restarts the entire Pod on a new node, discarding the emptyDir contents and any partially downloaded files.
Why it's wrong here
Init container failure is handled according to the Pod restartPolicy; the Pod is not necessarily moved to a new node. The emptyDir is retained while the Pod remains on the same node, so the statement about discarding contents on a new node is incorrect.
- ✗
The main container can start in parallel with the init container if the init container declares a readinessProbe, allowing faster startup.
Why it's wrong here
Init containers do not support readinessProbe, and app containers never start in parallel with init containers. The kubelet waits for every init container to complete successfully, so there is no mechanism to overlap init and main container startup.
- ✓
An emptyDir volume declared in the Pod spec can be mounted by both the init container and the main container, allowing files written by the init container to be visible to the main container.
Why this is correct
emptyDir is a Pod-scoped volume that exists for the Pod's lifetime and can be mounted into multiple containers. Mounting it in both the init container and the main container lets the init container write configuration files that the main container later reads, satisfying the shared-volume requirement.
- ✗
Init containers share the same network namespace as the main container, so they can bind to the same port the main container will use without conflict.
Why it's wrong here
Init containers do share the Pod network namespace, but they run before the main container and must exit before it starts. Binding to a port the main container later uses is not a conflict during init, but the statement implies simultaneous use, which is not how init containers work with app containers.
- ✓
Init containers run to completion one at a time before any app container starts, so the main container will not begin until the init container exits successfully.
Why this is correct
Init containers always run sequentially, and each must exit successfully before the next init container or any app container starts. This guarantees the configuration files are fully downloaded before the main application container begins, which is exactly the ordering the scenario requires.
Go deeper
Related to this question
Learn chapter
Multi-Container Pods and Sidecar Patterns
Key term
Init Containers
Init Containers are specialized containers that run and complete before the main containers in a Kubernetes Pod start, used for setup tasks like initializing data or waiting for dependencies.
Key term
Readiness Probes
A Kubernetes mechanism that checks if a container is ready to start accepting traffic and serve requests.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CNCF exam blueprint
This CKAD practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKAD exam.