Docker Quiz Test Online (30 random Questions) 2026

This quick 30-minute challenge consists of 30 random multiple-choice questions that test your knowledge across various Docker topics, including the introduction to Docker, installation procedures, Docker images and containers, networking, Docker Compose, advanced concepts, deployment in production, security, and integration with CI/CD pipelines. Whether you’re a beginner or have some experience, this quiz is designed to enhance your understanding of Docker’s capabilities in modern software development.

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30 Minutes Docker Quiz Test Online

Welcome to the Docker Quiz! This quick 30-minute challenge consists of 30 random multiple-choice questions that test your knowledge across various Docker topics, including the introduction to Docker, installation procedures, Docker images and containers, networking, Docker Compose, advanced concepts, deployment in production, security, and integration with CI/CD pipelines. Whether you're a beginner or have some experience, this quiz is designed to enhance your understanding of Docker's capabilities in modern software development.

1 / 30

1. What is the primary purpose of the CMD instruction in a Dockerfile?

A) CMD sets the base image

B) CMD is for environment variables

C) CMD provides default commands

D) CMD defines executable instructions

2 / 30

2. How do you copy files from a container to the host?

A) docker copy <container-id> <src-path>

B) docker export <container-id>

C) docker cp <container-id>:<src-path> <dest-path>

D) docker save <src-path> <dest-path>

3 / 30

3. What is a lightweight base image commonly used in Docker?

A) Ubuntu

B) Fedora

C) CentOS

D) Alpine

4 / 30

4. What happens to a container if it is stopped and not removed?

A) It is automatically deleted.

B) It is moved to an archive.

C) It cannot be restarted.

D) It remains on the system and can be restarted.

5 / 30

5. How do you stop all running services managed by Docker Compose?

A) docker-compose terminate

B) docker-compose stop

C) docker-compose down

D) docker-compose kill

6 / 30

6. What is the default Docker installation directory on Linux?

A) /var/lib/docker

B) /usr/docker

C) /etc/docker

D) /opt/docker

7 / 30

7. Which component of Docker is responsible for creating containers?

A) Docker Engine

B) Docker Compose

C) Docker Hub

D) Docker CLI

8 / 30

8. Which command is used to install Docker on macOS?

A) yum install docker

B) apt-get install docker

C) brew install docker

D) zypper install docker

9 / 30

9. What is the size of the default Docker Desktop installation?

A) ~2 GB

B) ~1 GB

C) ~200 MB

D) ~400 MB

10 / 30

10. What does the FROM instruction in a Dockerfile do?

A) Specifies the base image for the new Docker image

B) Copies files to the container

C) Sets the working directory in the container

D) Starts a new container

11 / 30

11. What is the purpose of the docker-compose.override.yml file?

A) To automate image builds

B) To define development-specific configurations

C) To replace Docker Compose

D) To deploy containers

12 / 30

12. What does the EXPOSE instruction in a Dockerfile do?

A) Publishes a port to the host machine

B) Specifies the ports the container listens on

C) Opens all container ports

D) Maps container ports to host ports

13 / 30

13. What happens if multiple CMD instructions are used in a Dockerfile?

A) All CMD instructions are executed sequentially.

B) Docker throws an error during the build process.

C) Only the first CMD instruction is executed.

D) The last CMD instruction overrides the previous ones.

14 / 30

14. Which of the following is a common orchestration tool used with Docker in production?

A) Jenkins

B) Ansible

C) Kubernetes

D) Terraform

15 / 30

15. What does Docker use to optimize image layers?

A) Layer caching

B) Hypervisor technology

C) Virtual memory

D) Volume mapping

16 / 30

16. What is the function of Docker Healthchecks?

A) To enforce network security policies

B) To validate container readiness and health

C) To check Docker daemon status

D) To monitor CPU and memory usage

17 / 30

17. Which of the following is NOT a recommended practice for running Docker containers in production?

A) Define resource limits

B) Limit container privileges

C) Use the root user in containers

D) Keep container images updated

18 / 30

18. Which instruction in a Dockerfile is used to run a command during the build process?

A) RUN

B) CMD

C) WORKDIR

D) ENTRYPOINT

19 / 30

19. What is the purpose of the restart key in Docker Compose?

A) To define the restart policy for containers

B) To automatically rebuild the container

C) To enable scaling of services

D) To restart the Docker service

20 / 30

20. What does the term "containerized CI/CD" mean?

A) Avoiding orchestration tools

B) Automating code commits

C) Deploying containers without testing

D) Running CI/CD processes inside Docker containers

21 / 30

21. What does the docker pull command do?

A) Deletes a Docker image

B) Downloads a Docker image from a registry

C) Creates a new Docker image

D) Runs a container from a Docker image

22 / 30

22. Which Docker feature isolates containers at the kernel level?

A) Namespaces

B) Overlay network

C) Docker Compose

D) Control groups (cgroups)

23 / 30

23. What is the default storage driver for Docker on Linux?

A) OverlayFS

B) Btrfs

C) Device Mapper

D) AUFS

24 / 30

24. Which command inspects the IP address of a running container?

A) docker network ip

B) docker ip <container>

C) docker inspect <container>

D) docker ps

25 / 30

25. How do you define custom networks in Docker Compose?

A) Using the docker network create command

B) Under the networks key in docker-compose.yml

C) By defining them in the container

D) Automatically generated by Compose

26 / 30

26. Which command is used to build a Docker image from a Dockerfile?

A) docker create

B) docker build

C) docker image

D) docker run

27 / 30

27. What does the docker secret command manage in a Docker Swarm?

A) Encrypted secrets for services

B) Multi-stage build configurations

C) API keys for Kubernetes

D) TLS certificates

28 / 30

28. What is the default port on which Docker Daemon listens for API requests?

A) 8080

B) 2375

C) 443

D) 22

29 / 30

29. How can you restart a stopped container?

A) docker init <container-id>

B) docker restart <container-id>

C) docker start <container-id>

D) docker run <container-id>

30 / 30

30. How can Docker ensure application rollback in a CI/CD pipeline?

A) By saving previous container logs

B) By using a versioned Docker image from the registry

C) By creating snapshots of running containers

D) By monitoring container health

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