Docker Interview Questions

What is Docker and how is it different from a Virtual Machine?

What is the difference between a Docker Image and a Docker Container?

What is a Dockerfile? Explain key instructions.

What are Docker Volumes? Why are they needed?

What is Docker Compose and when would you use it?

What is Docker Hub and how do you use docker pull and docker push?

What does docker exec do and how is it used?

What does docker ps show and what are its useful flags?

How does port mapping work in Docker with the -p flag?

How do you pass environment variables to Docker containers?

What is .dockerignore and why is it important?

What is Docker Desktop and how does it differ from Docker Engine?

Explain the Docker container lifecycle and key state transitions.

What does docker inspect do and how do you use it effectively?

What is the container-to-host port mapping process and how does EXPOSE work?

Explain Docker networking modes.

What is the difference between CMD and ENTRYPOINT in a Dockerfile?

What are multi-stage builds in Docker and why are they important?

How do you reduce Docker image size?

What is Docker layer caching and how do you optimize it?

What is Docker Swarm and how does it compare to Kubernetes?

How do overlay networks work in Docker Swarm?

How do you implement health checks in a Dockerfile?

What is Docker context and how do you manage multiple Docker environments?

What is a Docker registry mirror and why would you set one up?

How do you scan Docker images for vulnerabilities?

How do you set resource limits (CPU and memory) on Docker containers?

What is the Docker socket and why is it important?

What is the difference between bridge and host networking in Docker? When would you use each?

What are Docker secrets and how do you manage sensitive data?

What are tmpfs mounts in Docker and when should you use them?

What is Docker Bench for Security and how do you use it?

What is a good Docker image tagging strategy for production?

How do you implement Docker security best practices in production?

Explain Docker's copy-on-write (CoW) mechanism.

How would you set up a production-grade Docker logging strategy?

What is Docker BuildKit and what advantages does it offer over the classic builder?

How do you debug a Docker container that exits immediately or behaves unexpectedly?

How does Docker rootless mode work and why is it important?

What is the difference between containerd and CRI-O as container runtimes?

What is Docker in Docker (DinD) and what are the alternatives?

How do you secure the Docker socket and what are the risks of exposing it?

How do custom bridge networks work in Docker and why are they preferred over the default bridge?

What is Docker Content Trust (DCT) and how does image signing work?

What is Docker live restore and how does it affect container availability?

How do you configure the Docker daemon and what are the most important settings?

What are Docker storage drivers and how do overlay2 and devicemapper compare?

How does Docker compare to Kubernetes, Docker Swarm, and other orchestration tools for production?

How do you interact with the Docker API directly and what can you do with it?

What is an AI-powered Docker image and how are LLMs being used in container workflows?