Following is the list of frequently asked Docker interview questions and answers in 2025. This list is curated from actual interview questions asked recently in Devops/SRE/MLOps/Cloud related roles.
It is HIGHLY recommended that you go through our useful Docker Resources first, which explains Docker as a whole conceptually.
Docker Concepts
What is Docker, and why is it used?
What is Docker, and how does it differ from a virtual machine (VM)?
Why we use Docker and What problem does Docker solve?
What is the role of the Docker daemon?
What is the Docker registry, and how do you use it?
How can you reduce the size of your Docker image effectively?
How does Docker achieve isolation between containers?
Explain the concept of multi-stage builds in Docker.
What are the main components of Docker
Anatomy of docker run command. OR What happens when you run the command “docker run <image name>” command
How do you debug a failed container
Docker Containers and Images
What is a Docker container?
Whatโs the difference between a Docker image and a Docker container?
How can you reduce the size of your Docker image effectively?
How does Docker achieve isolation between containers?
How can you limit the resources (CPU, memory, etc.) for a Docker container?
What are the different Docker image layers, and how do they work?
How can you troubleshoot Docker containers?
How do you start, stop and remove a docker container?
What is the Docker registry, and how do you use it?
How can you deploy Docker containers in production?
How do you authenticate with a private docker registry
DockerFile
What is a Dockerfile, and how do you use it to build images?
What is the role of CMD vs ENTRYPOINT in a Dockerfile?
Difference between COPY and ADD in DockerFile
What is a multi-stage build, how would you optimize a Dockerfile, and why is it important?
Explain the concept of multi-stage builds in Docker.
How would you write a Dockerfile to build a Node.js project?
Why is it beneficial to copy ๐ฝ๐ฎ๐ฐ๐ธ๐ฎ๐ด๐ฒ.๐ท๐๐ผ๐ป before other files in a Dockerfile?
Given:
ENTRYPOINT [“echo”]
CMD [“HELLO-WORLD”]
What will be the output? Explain why.
Docker Volumes
Why we use volume in docker.
What are Docker volumes, and why are they used?
What are the different types of Docker storage drivers?
How do you handle data persistence in Docker containers?
How do you persist data in Docker using volumes or bind mounts?
How do you check all available volumes
How do you remove unused volumes
How do you share a volume between multiple containers
How do you persist data across container restarts
How to make a volume read only
What happens if you delete a volume while a container is using it
Docker Compose
What is Docker Compose, and how is it useful in multi-container applications?
Have you worked with Docker Compose? Explain in details your project and what challenges you faced
How do you start and stop services in docker compose
How do you update a running service in docker compose
How do you scale services using docker compose
How do you specify environment variable in docker compose
Docker Commands
How do you view running vs stopped containers using Docker CLI?
What is the difference between docker stop and docker kill?
What is the difference between the docker run and docker exec commands?
How do you access shell of a running container
What is the purpose of the docker ps command?
Difference between docker run and docker start?
How do you list all running and stopped containers
Commands to run a container in background
What happens when you run the command “docker run <image name>”
Command to check logs of a running container
what is docker scan command used for
How to forcibly remove an image
command to clean up unused docker resources
Command to analyze docker container resource usage
Docker Networking
How do you expose container ports to make services accessible outside Docker?
What is a Docker network, and how do you create one?
How do you list all docker networks
Difference between Bridge, Host and Overlay networks
How do you connect a container to a specific network
How to block external network access for a container
Docker Swarm/Orchestration
What is the role of a container orchestration platform like Kubernetes in Docker?
How do you initialize a docker swarm cluster
What is Docker Swarm?
How does Docker Swarm work?
What are the benefits of using Docker Swarm?
How do you create a Docker Swarm cluster?
What is a service in Docker Swarm?
How do you deploy a service in Docker Swarm?
What is the difference between Docker Swarm and Kubernetes?
How do you manage node availability in Docker Swarm?
What is load balancing in Docker Swarm?
How do you monitor Docker Swarm?
Docker Security
How would you perform a security scan on a Docker image?
How would you secure a MySQL database running in a Docker container?
How do you run a container with limited privileges
How do you enforce security policies in Docker