Top 35 Docker Interview Questions & Answers- Talent Economy

If you’re searching for Docker interview questions & answers below, we have mentioned the 35 interview questions which a candidate can go through.

1. What is Docker?

It is a set of PaaS (product as a service) products which allow building, testing and deploying applications quickly and easily.  It uses operating-system-level virtualization to deliver software in packages called containers.

2. Name some features of Docker?

Some important features of Docker are:

  • Version Control
  • Easy Modeling
  • Application Agility
  • Developer Productivity
  • Operational Efficiencies
  • Placement

3. Explain the Docker image?

Docker image helps to create docker containers. You can devise the docker image with the build command. Due to this, it creates a container that starts when it begins to run. Every docker images are stored in the docker registry.

4. What is the memory swap flag?

Memory swap is a changed flag that only has meaning if memory is also set. Swap allows the container to write express memory requirements to disk when the container has exhausted the entire RAM which is available to it.

5. Define Registries?

There are two types of registry:

  • Private Registry
  • Public Registry

6. What the states of docker container?

Important states of Docker container are:

  • Paused
  • Exited
  • Running
  • Restarting

7. Define Hypervisor?

The hypervisor permits you to construct virtual surroundings in which the guest virtual machines operate. It controls the guests’ system and checks if the resources are allocated to the guests as necessary.

8. Can you lose data when the container exists?

No, any data that your application writes to the disk get stored in the container. The file system for the contain persists even after the container halts.

9. What is a different kind of volume mount types available in Docker?

Blind mounts- It can be stored anywhere on the host system

10. What is the client?

Docker provides command-line interface tools to the client to interact with Docker daemon.

11. What do you mean by docker hub?

Docker image creates docker containers. There has to be a registry where these docker images live. The registry is Docker Hub. Users can pick up images from Docker Hub and use them to create customized images and containers.

12. How can you run multiple containers using a single service?

By using docker-compose, you can run multiple containers using a single service. All Dockers compose files uses yaml language.

13. What are the three components of Docker Architecture?

The three components are:

  • Docker- Host
  • Client
  • Registry

14. What are the steps for the docker container lifecycle?

Below are the steps for the docker container life cycle:

  • Build
  • Pull
  • Run

15. State the difference between virtualization and containerization?

Virtualization is a conceptual version of a corporeal machine, while containerization is the conceptual version of an application

16. What are docker object labels?

Labels are the device for applying metadata to Docker objects such as containers, images, local daemons, networks, quantities, and nodes.

17. How do you check the versions of docker client and server?

This command provides you with all the information you need: $ docker version

18. Tell me something about the docker system prune?

It’s an authority used to eliminate all stopped containers, unused networks, build caches, and hanging images. Prune is one of the most practical commands in Docker. The syntax is $ docker system prune.

19. Can a container restart on its own?

  Since the default flag -reset is set to false; a container cannot restart by itself.

20. Define the Docker Engine?

Docker engine symbolizes the server. The docker daemon and the clients should be a sprint on the same or distant host, which can converse through command-line client binary and full Restful API.

21. Explain Docker swarm?

Docker Swarm is resident gathering for docker which assists you to a cluster of Docker hosts into a solitary and virtual docker host. It offers the average docker application program interface.

22. What is the command to control Docker with Systemd?

Systemctl start/stop docker

Service docker start/stop

23. How to include code with copy/add or volumes?

In docker file, we require to use COPY or ADD instruction. This is useful to move code. However, we should use a quantity if we want to make changes.

24. What is CNM?

CNM refers to Container Networking Model. It is a standard from Docker, Inc. that forms the foundation of container networking in a Docker environment. This docker’s loom provides container networking withhold for manifold network drivers.

25. How to configure the default logging driver under Docker?

To arrange the Docker daemon to non-payment to a precise logging driver. You need to set the worth of log-driver to the name of the logging drive the daemon.jason.fie.

26. What is the command you need to give to push the new image to the Docker registry?

docker push myorg/img

27. How does communication happen between Docker client and Docker Daemon?

You can converse between Docker client and Docker Daemon with the grouping of Rest API, socket.IO, and TCP.

28. Write a docker file to create and copy a directory and built it using python modules?

FROM python: 2.7-slim


COPY. /app

Docker build –tag

29. Where the docker volumes are stored?

You need to navigate:


30. Define Docker Machine?

Docker machine is a tool that lets you put in Docker Engine on practical hosts. These hosts can now be managed using the docker-machine commands. Docker machine also lets you stipulation Docker Swarm Clusters.

31. How to log in into the docker repository?

You can use the following command to login into

$ docker login

You’ll be encouraged for your username and password, place in those and congratulations; you’re logged in.

32. How to delete a stopped container?

Use the following command to delete a stopped container:

$ Docker rm

33. How to build a docker file?

Once you’ve printed a Dockerfile, you need to construct it to craft an image with those specifications. Use the following rule to build a Dockerfile:

$ Docker build

The next question would be when do you use “.dockerfile_name” and when to use the entire path?

Use “.dockerfile_name” when the Dockerfile exits in the same file directory and you use the entire path if it lives somewhere else.

34. How will you monitor Docker in production?

Docker provides functionalities like docker stats and docker events to check docker in production. Docker stats provides CPU and memory practice of the container. Docker events offer information about the activities taking rest in the docker daemon.

35. What is the purpose of Docker_Host?

It contains container, images, and Docker daemon. It offers an absolute environment to perform and run your application.

Above are the interview questions and answers related to docker jobs. Candidates who are willing to apply for the job should prepare well before going for an interview.

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