CKAD Application Design and Build Practice Test 3 — 15 Questions

Question 1

A user runs 'kubectl run nginx --image=nginx --restart=Never' and the pod goes into 'Pending' state. What is a likely reason?

Accepted Answer

The node has insufficient resources to schedule the pod. Pending often indicates resource constraints like insufficient CPU or memory.

Answer

The image name is incorrect

Answer

The pod is missing a readiness probe

Answer

The pod's restart policy is set to Never

Question 2

A CronJob is configured with 'concurrencyPolicy: Forbid'. If a job from the previous schedule is still running when the next scheduled time arrives, what happens?

Accepted Answer

The new job is skipped until the old job completes. When `concurrencyPolicy: Forbid` is set on a CronJob, the CronJob controller will skip creating a new Job if the previous Job from the last schedule is still running. The new Job is effectively skipped (not queued) until the next scheduled time, preventing overlapping executions. This ensures that only one instance of the Job runs at a time.

Answer

The CronJob is suspended

Answer

The new job starts immediately, and the old job is terminated

Answer

Both jobs run concurrently

Question 3

A user creates a Job with '.spec.completions=5' and '.spec.parallelism=2'. How many pods will run at the same time?

Accepted Answer

2. `.spec.parallelism=2` directly specifies the maximum number of Pods that can run concurrently for the Job. The `.spec.completions=5` value only sets the total number of successful completions required, not the parallelism. Therefore, at any given time, only 2 Pods will run simultaneously.

Answer

5

Answer

10

Answer

7

Question 4

You need to debug a pod that has no running container because it crashed. The pod is in CrashLoopBackOff. Which command allows you to start a temporary container in the same pod for debugging?

Accepted Answer

kubectl debug <pod> -it --image=busybox. `kubectl debug` can create an ephemeral container in an existing pod for debugging purposes, even when the original container is in CrashLoopBackOff. The `-it` flag provides an interactive terminal, and `--image=busybox` supplies a lightweight debugging image. This allows you to inspect the pod's filesystem, network, or environment without restarting the failing container.

Answer

kubectl attach <pod>

Answer

kubectl run debug --image=busybox

Answer

kubectl exec -it <pod> -- /bin/bash

Question 5

What is the default restart policy for a pod created with 'kubectl run nginx --image=nginx'?

Accepted Answer

Always. The default restart policy for a Pod created with `kubectl run` is `Always`. This is because `kubectl run` generates a deployment-like controller (or a standalone Pod in older versions) that defaults to the `Always` policy, meaning the kubelet will automatically restart the container regardless of its exit code. This ensures the Pod maintains a running state unless explicitly deleted or scaled down.

Answer

OnFailure

Answer

Never

Answer

Restart

Question 6

Which TWO of the following are valid patterns for sidecar containers in a multi-container pod?

Accepted Answer

Adapter. The sidecar pattern involves adding a helper container to a pod. The two common patterns are Adapter and Sidecar. Adapter pattern standardizes output, while Sidecar pattern provides auxiliary functionality. Ambassador is also a sidecar pattern, but this question specifically asks for two correct answers among the options, and Adapter and Sidecar are the correct choices.

Answer

Ambassador

Answer

Init container

Answer

Proxy

Question 7

Which THREE of the following are valid fields in the '.spec' of a Job manifest?

Accepted Answer

parallelism. 'parallelism' is a valid field in the '.spec' of a Job manifest. It controls the maximum number of Pods that can run concurrently for the Job, allowing you to manage parallel execution. This field is part of the Job specification in the Kubernetes API, distinct from Deployments or other controllers.

Answer

replicas

Answer

strategy

Question 8

Which command builds a Docker image from the current directory and tags it as 'myapp:v1'?

Accepted Answer

docker build -t myapp:v1 .. The `docker build` command requires both the `-t` flag to specify the image tag (name:version) and the build context path (`.` for the current directory). The syntax `docker build -t myapp:v1 .` correctly tags the image as 'myapp:v1' and uses the current directory as the build context, which includes the Dockerfile and any referenced files.

Answer

docker build .

Answer

docker build -t myapp:v1

Answer

docker push myapp:v1

Question 9

You need to run a database migration as a container before the main application container starts. Which Kubernetes concept should you use?

Accepted Answer

Init container. Init containers run sequentially before the main application container starts and are designed for setup tasks like database migrations. They complete successfully before any regular containers in the Pod begin, ensuring the migration finishes before the main app starts.

Answer

Job

Answer

Sidecar container

Answer

Ephemeral container

Question 10

A pod has an init container that fails. The status shows 'Init:CrashLoopBackOff'. The pod's restartPolicy is 'Always'. What happens to the init container?

Accepted Answer

The init container will restart until it succeeds. Init containers always run to completion before any main containers start, and they are restarted until they succeed regardless of the pod's restartPolicy. The restartPolicy only applies to main containers, not init containers. When an init container fails, Kubernetes restarts it indefinitely until it exits with a zero status, which is why the status shows 'Init:CrashLoopBackOff'.

Answer

The pod will be deleted and recreated

Answer

The main containers will start anyway

Answer

The init container will not restart because the pod's restartPolicy is Always

Question 11

A Job must run 10 times in total, with up to 3 pods running simultaneously. Which fields should be set?

Accepted Answer

completions: 10, parallelism: 3. In a Kubernetes Job, `completions: 10` specifies the total number of successful Pod completions required, and `parallelism: 3` limits the number of Pods that can run concurrently. This ensures the Job runs exactly 10 times with up to 3 Pods in parallel, which matches the requirement.

Answer

completions: 10, successfulJobsHistoryLimit: 3

Answer

completions: 10, parallelism: 10

Answer

completions: 3, parallelism: 10

Question 12

You want to expose a container's port 8080 in the Dockerfile. Which instruction should you use?

Accepted Answer

EXPOSE 8080. The `EXPOSE` instruction in a Dockerfile informs Docker that the container listens on the specified network port at runtime. It is a metadata declaration that does not actually publish the port; it serves documentation and inter-container communication purposes via Docker networks.

Answer

PORT 8080

Answer

LISTEN 8080

Answer

PUBLISH 8080

Question 13

Which instruction in a Dockerfile sets the default command to run when the container starts, but allows overriding?

Accepted Answer

CMD. The CMD instruction in a Dockerfile defines the default command to execute when a container starts from the image. It can be overridden by providing a command at the end of the `docker run` command, making it the correct choice for a default command that allows user override.

Answer

START

Answer

RUN

Answer

ENTRYPOINT

Question 14

A multi-stage build has two stages named 'builder' and 'final'. Which instruction copies artifacts from the builder stage to the final stage?

Accepted Answer

COPY --from=builder /app /app. In a multi-stage Docker build, the COPY instruction with the --from flag allows you to copy files from a named previous stage (here 'builder') into the current stage ('final'). This is the correct syntax to selectively transfer build artifacts without carrying over intermediate layers or dependencies.

Answer

FROM builder /app /app

Answer

COPY builder /app /app

Answer

ADD --from=builder /app /app

Question 15

A pod named 'webapp' is stuck in 'Pending' state. 'kubectl describe pod webapp' shows '0/1 nodes are available: 1 Insufficient memory'. What is the most likely cause?

Accepted Answer

The pod's memory request exceeds available node memory. The error message '0/1 nodes are available: 1 Insufficient memory' directly indicates that the pod's memory request exceeds the allocatable memory on the node. The scheduler cannot place the pod because no node has enough unallocated memory to satisfy the pod's memory request. This is a scheduling failure, not a runtime issue.

Answer

The node has insufficient CPU

Answer

The container was killed due to out-of-memory

Answer

The container image does not exist