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 purpose of using multi-stage builds in Docker security?

A) To automatically deploy containers

B) To improve container startup time

C) To increase the number of layers in the image

D) To reduce image size and exclude unnecessary dependencies

2 / 30

2. How do you update a running container's configuration in Docker Compose?

A) Use the docker-compose update command

B) Edit the container configuration manually

C) Rebuild the container and restart using docker-compose up --build

D) Restart the container

3 / 30

3. Which of the following tools can help enforce Docker image security policies?

A) Jenkins

B) Docker Content Trust

C) Docker Compose

D) Kubernetes

4 / 30

4. What does the --rm flag do when running a Docker container?

A) Prunes unused volumes

B) Deletes all stopped containers

C) Removes dangling images

D) Automatically removes the container after it stops

5 / 30

5. What is the function of cgroups in Docker?

A) Enforces resource limits for containers

B) Validates image signatures

C) Manages Swarm secrets

D) Isolates containers on a network

6 / 30

6. What is the difference between a Docker image and a container?

A) A container is a running instance of an image

B) An image is a running instance of a container

C) Containers and images are the same

D) Images store logs, while containers run processes

7 / 30

7. What was Docker originally called during its development?

A) dotContainer

B) The Docker Project

C) Container Engine

D) dotCloud

8 / 30

8. What is the default working directory inside a container?

A) / (root directory)

B) /var

C) /root

D) /home

9 / 30

9. Which file format is used to define a Docker image?

A) XML

B) YAML

C) Dockerfile

D) JSON

10 / 30

10. What is the purpose of the docker pull command?

A) To create a new container

B) To list all available images

C) To remove an image

D) To download an image from a registry

11 / 30

11. 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

12 / 30

12. How do you connect a running container to an existing network?

A) docker connect <network> <container>

B) docker network attach <network> <container>

C) docker attach <network> <container>

D) docker network connect <network> <container>

13 / 30

13. How does Docker simplify CI/CD pipelines?

A) By providing consistent environments for development, testing, and production

B) By replacing version control systems

C) By eliminating the need for orchestration tools

D) By reducing the need for code reviews

14 / 30

14. Which of the following is a common step in Docker-based CI/CD pipelines?

A) Container orchestration

B) All of the above

C) Image version tagging

D) Image scanning for vulnerabilities

15 / 30

15. How do you stop a running Docker container?

A) docker end <container-id>

B) docker pause <container-id>

C) docker stop <container-id>

D) docker terminate <container-id>

16 / 30

16. Which storage option allows Docker volumes to persist across host machines?

A) tmpfs

B) Bind Mounts

C) Overlay Network

D) NFS or External Storage Drivers

17 / 30

17. Why is tagging Docker images important in CI/CD pipelines?

A) To uniquely identify and version images

B) To reduce image size

C) To encrypt image layers

D) To improve build speed

18 / 30

18. What does the docker stack ps command display?

A) Health status of the stack

B) Status of tasks in a stack

C) Running containers in a stack

D) Logs of a stack's services

19 / 30

19. What is the primary reason for setting resource limits in Docker containers?

A) To improve the container's performance

B) To enable container orchestration

C) To restrict unauthorized network access

D) To prevent containers from exhausting host resources

20 / 30

20. What is the name of the tool used to define multi-container applications?

A) Docker CLI

B) Docker Compose

C) Docker Hub

D) Docker Engine

21 / 30

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

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

B) It cannot be restarted.

C) It is automatically deleted.

D) It is moved to an archive.

22 / 30

22. How do you specify environment variables in a Docker Compose file?

A) Using the environment key

B) Using the config key

C) Using the env key

D) Using the variables key

23 / 30

23. What happens if Docker is installed on a system without enough disk space?

A) Docker will refuse to install.

B) Docker will install but fail to run containers.

C) Docker will prompt for manual disk space allocation.

D) Docker will disable image caching.

24 / 30

24. Which Docker logging driver is commonly used in production for centralized log management?

A) none

B) Fluentd

C) JSON-file

D) syslog

25 / 30

25. What is the function of Docker Healthchecks?

A) To check Docker daemon status

B) To enforce network security policies

C) To validate container readiness and health

D) To monitor CPU and memory usage

26 / 30

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

A) Control groups (cgroups)

B) Overlay network

C) Namespaces

D) Docker Compose

27 / 30

27. What is the default restart policy for a container?

A) No

B) Unless-stopped

C) Always

D) On-failure

28 / 30

28. 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

29 / 30

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

A) To enable scaling of services

B) To restart the Docker service

C) To automatically rebuild the container

D) To define the restart policy for containers

30 / 30

30. What is the function of the Docker --privileged flag?

A) Disables network communication for the container

B) Sets resource limits for the container

C) Grants a container root access to the host

D) Encrypts container data

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