CKAD Application Design and Build Practice Test 4 — 15 Questions

Question 1

Which command attaches an ephemeral container to a running pod for debugging?

Accepted Answer

kubectl debug -it mypod --image=busybox --target=mycontainer. `kubectl debug` with `-it` and `--image=busybox` creates an ephemeral container in the target pod for interactive debugging, while `--target=mycontainer` attaches the ephemeral container to the same network and process namespace as the specified container. This is the only command that adds a new, temporary container to a running pod without restarting it, which is essential when the existing container lacks debugging tools or is in a crash loop.

Answer

kubectl attach mypod

Answer

kubectl exec -it mypod -- sh

Answer

kubectl logs mypod -c mycontainer

Question 2

Which TWO practices optimize Docker image size? (Select 2)

Accepted Answer

Including a .dockerignore file to exclude unnecessary files. A `.dockerignore` file prevents unnecessary files (e.g., local logs, node_modules, .git) from being sent to the Docker daemon during the `docker build` context, reducing the build context size and avoiding bloating the image with irrelevant data. Option D is correct because multi-stage builds allow you to compile or install dependencies in a temporary stage and then copy only the final runtime artifacts (e.g., compiled binaries) into a minimal final image, discarding build tools and intermediate layers.

Answer

Running 'apt-get upgrade' in the Dockerfile

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Using a full OS base image like ubuntu:latest

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Installing all packages in one layer without cleanup

Question 3

Which THREE statements are true about init containers? (Select 3)

Accepted Answer

Init containers must complete successfully before any main container starts. Init containers are specialized containers that run to completion before any main application containers in the pod start. They must exit with a zero status (success) for the pod to proceed to the next init container or to start the main containers. This ensures prerequisite setup tasks are completed before the application runs.

Answer

Init containers support liveness and readiness probes

Answer

Init containers cannot have resource limits

Question 4

Which TWO fields are required in a CronJob manifest? (Select 2)

Accepted Answer

schedule. The `schedule` field defines the cron expression that determines when the CronJob runs (e.g., `*/5 * * * *`). This is a mandatory field in a CronJob manifest as per the Kubernetes API specification, without which the controller cannot determine the execution timing.

Answer

startingDeadlineSeconds

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successfulJobsHistoryLimit

Answer

concurrencyPolicy

Question 5

Which of the following commands creates a Job that runs a single pod executing the command 'sleep 30'?

Accepted Answer

kubectl create job myjob --image=busybox -- sleep 30. `kubectl create job myjob --image=busybox -- sleep 30` creates a Job object that runs a single Pod executing the command `sleep 30`. The `--` separator indicates the end of kubectl options and the start of the container command, which is the correct syntax for passing a command to the Job's container.

Answer

kubectl run myjob --image=busybox --restart=OnFailure -- sleep 30

Answer

kubectl create job myjob --image=busybox --command -- sleep 30

Answer

kubectl create job myjob --image=busybox sleep 30

Question 6

You have a multi-stage Dockerfile for a Go application. The first stage compiles the binary, and the second stage uses a scratch image. Which of the following is the correct way to copy the binary from the first stage into the second stage?

Accepted Answer

COPY --from=builder /app/bin /app/. `COPY --from=builder` references a named stage in a multi-stage Dockerfile. Option D is incorrect because in the CKAD exam, stage numbers are not used; only named stages are valid for the `--from` flag. Using the index `0` is not supported in the expected syntax and would cause a build error.

Answer

ADD --from=builder /app/bin /app/

Answer

COPY /app/bin /app/

Answer

COPY --from=0 /app/bin /app/

Question 7

A Kubernetes Job with parallelism=3 and completions=6 is created. How many pods will run concurrently at most?

Accepted Answer

3. The `parallelism` field in a Kubernetes Job specifies the maximum number of pods that can run concurrently. With `parallelism=3`, at most 3 pods will run at the same time, regardless of the total number of completions required.

Answer

9

Answer

6

Answer

1

Question 8

Which field in a CronJob spec specifies the maximum number of successful jobs that should be retained?

Accepted Answer

.spec.successfulJobsHistoryLimit. The `.spec.successfulJobsHistoryLimit` field in a CronJob spec explicitly controls the number of successful jobs that are retained after completion. This field defaults to 3 and, when set to 0, suppresses the retention of any successful job history, directly managing cluster resource usage by limiting the accumulation of completed Pods.

Answer

.spec.jobTemplate.spec.backoffLimit

Answer

.spec.jobHistory.succeeded

Answer

.spec.history.successfulJobsLimit

Question 9

You need to debug a pod that has no shell installed. You want to add a temporary container with debugging tools to the pod. Which command should you use?

Accepted Answer

kubectl debug mypod -it --image=busybox -- /bin/sh. `kubectl debug mypod -it --image=busybox -- /bin/sh` creates an ephemeral container in the existing pod `mypod`, attaching it interactively with a shell. This allows you to debug a pod that lacks a shell or debugging tools without modifying the original container's image or restarting the pod.

Answer

kubectl run debug --image=busybox -it -- /bin/sh

Answer

kubectl debug mypod --image=busybox --target=debug -n default

Answer

kubectl exec -it mypod -- /bin/sh

Question 10

What is the purpose of an init container in a pod?

Accepted Answer

To run to completion before the main containers start, often for initialization tasks. Init containers run to completion sequentially before any main containers in the pod start. They are designed for initialization tasks such as setting up databases, waiting for external services, or populating configuration files. Unlike sidecar containers, they do not run alongside the main containers and must exit successfully before the pod transitions to the Running phase.

Answer

To check the health of the main container and restart it if necessary

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To run alongside the main container and provide additional services

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To run a command after the main container starts

Question 11

A CronJob has concurrencyPolicy set to 'Forbid'. At the scheduled time, if the previous job is still running, what happens?

Accepted Answer

The new job is skipped (does not run). When a CronJob has `concurrencyPolicy: Forbid`, Kubernetes ensures that if a previous job instance is still running at the next scheduled time, the new job is simply skipped (does not run). This prevents overlapping executions, which is critical for workloads that must not run concurrently, such as database migrations or batch processing that would cause data corruption.

Answer

The new job is delayed until the previous job completes

Answer

Both jobs run concurrently

Answer

The previous job is terminated and the new job starts

Question 12

Which of the following is the correct way to set a memory limit of 512Mi for a container in a pod spec?

Accepted Answer

resources.limits.memory: 512Mi. `resources.limits.memory` is the Kubernetes field used to set the maximum amount of memory a container is allowed to use. When a container exceeds this limit, it may be terminated or OOM-killed. The value `512Mi` specifies 512 mebibytes, which is a binary-based unit commonly used in Kubernetes resource specifications.

Answer

resources.requests.memory: 512Mi

Answer

resources.requests.limits.memory: 512Mi

Answer

resources.limits.cpu: 512Mi

Question 13

Which of the following Dockerfile instructions is used to set a command that runs when the container starts and can be overridden by command-line arguments?

Accepted Answer

CMD. The CMD instruction in a Dockerfile provides default command(s) for the executing container. When a user runs `docker run image [COMMAND]`, the provided COMMAND overrides the CMD value, making it the correct choice for a command that can be overridden by command-line arguments.

Answer

EXPOSE

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COPY

Answer

RUN

Question 14

Which TWO of the following are valid fields in a Job spec? (Select TWO.)

Accepted Answer

backoffLimit. Options B (backoffLimit) and E (parallelism) are correct fields in a Job spec. 'backoffLimit' controls the number of retries before marking the Job as failed, and 'parallelism' specifies the maximum number of Pods running in parallel. Option A (replicas) is a field for Deployments, not Jobs. Option C (schedule) is used in CronJobs. Option D (restartPolicy) is a Pod-level field; in Jobs, the restartPolicy is defaulted to OnFailure or Never but is not a top-level Job spec field.

Answer

replicas

Answer

schedule

Answer

restartPolicy

Question 15

Which THREE of the following are correct about init containers? (Select THREE.)

Accepted Answer

They run to completion before the main application containers start. Init containers are designed to run sequentially to completion before any of the pod's regular application containers start. This ensures that prerequisites, such as database schema migrations or configuration file generation, are completed before the main application begins execution.

Answer

They cannot have resource limits set

Answer

They run after the main application containers have started