Docker Interview Questions

Docker interview questions

When it comes to cracking an interview, you will need to put a lot of efforts and use your knowledge to crack it. Cracking an interview will definitely help you in giving a structure to your career as you will be sitting in an office, knowing about your career development procedures, and earn a good amount of money per month to support your family and yourselves. You need not have to depend on anyone, and we do understand that. Therefore, our experts and professionals have come up with docker interview questions and answers that will assist you in preparing for the interview and crack it.

About Docker

Docker is basically a set of multiple SaaS (Software as a Service) and PaaS (Platform as a Service) products that utilize the OS-level system of virtualization to build and deliver software in many packages, known as containers. The software that is hosting the containers is known as Docker engines. It was initially introduced in the year of 2013 and is created by the Docker Inc. company. It offers both the services, free as well as premium where you have the option to choose the best one depending on your demands and requirements.

Best Docker Interview Questions of 2020

1. What is Docker?

Docker is an open-source lightweight containerization technology. It has gained widespread popularity in the cloud and application packaging world. It allows you to automate the deployment of applications in lightweight and portable containers.

2. What are the advantages of using Docker container?

Here, are a major advantage of using Docker.

  • Offers an efficient and easy initial set up
  • Allows you to describe your application lifecycle in detail
  • Simple configuration and interacts with Docker Compose.
  • Documentation provides every bit of information.

3. What are the important features of Docker?

Here are the essential features of Docker:

  • Easy Modeling
  • Version control
  • Placement/Affinity
  • Application Agility
  • Developer Productivity
  • Operational Efficiencies

4. What are the main drawbacks of Docker?

Some notable drawbacks of Docker are:

  • Doesn't provide a storage option
  • Offer a poor monitoring option.
  • No automatic rescheduling of inactive Nodes
  • Complicated automatic horizontal scaling set up

5. What is Docker image?

The Docker image help to create Docker containers. You can create 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.

6. What is Docker Engine?

Docker daemon or Docker engine represents the server. The docker daemon and the clients should be run on the same or remote host, which can communicate through command-line client binary and full RESTful API.

7. Explain Registries

Docker's public registry is called Docker hub, which allows you to store images privately. In Docker hub, you can store millions of images.

8. What command should you run to see all running container in Docker?

$ docker ps

9. Write the command to stop the docker container

$ sudo docker stop container name

10. What is the command to run the image as a container?

$ sudo docker run -i -t alpine /bin/bash

11. What are the common instruction in Dockerfile?

The common instruction in Dockerfile are: FROM, LABEL, RUN, and CMD.

12. What is memory-swap flag?

Memory-swap is a modified 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 all the RAM which is available to it.

13. Explain Docker Swarm?   

Docker Swarm is native gathering for docker which helps you to a group of Docker hosts into a single and virtual docker host. It offers the standard docker application program interface.

14. How can you monitor the docker in production environments?

Docker states and Docker Events are used to monitoring docker in the production environment.

16. What the states of Docker container?

Important states of Docker container are:

  • Running
  • Paused
  • Restarting
  • Exited

17. What is Docker hub?

Docker hub is a cloud-based registry that which helps you to link to code repositories. It allows you to build, test, store your image in Docker cloud. You can also deploy the image to your host with the help of Docker hub.

18. Explain Docker object labels

Docker object labels is a method for applying metadata to docker objects including, images, containers, volumes, network, swam nodes, and services.

19. Write a Docker file to create and copy a directory and built it using python modules?

FROM pyhton:2.7-slim

WORKDIR /app

COPY . /app

docker build –tag

20. Where the docker volumes are stored?

You need to navigate:

 /var/lib/docker/volumes

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

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

22. Explain Implementation method of Continuous Integration(CI) and Continues Development (CD) in Docker?

You need to do the following things:

  • Runs Jenkins on docker
  • You can run integration tests in Jenkins using docker-compose

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

In docker file, we need to use COPY or ADD directive. This is useful to relocate code. However, we should use a volume if we want to make changes.

24. Explain the process of scaling your Docker containers

The Docker containers can be scaled to any level starting from a few hundred to even thousands or millions of containers. The only condition for this is that the containers need the memory and the OS at all times, and there should not be a constraint when the Docker is getting scaled.

25. What are the steps for the Docker container life cycle?

Below are the steps for Docker life cycle:

  • Build
  • Pull
  • Run

26. What is CNM?

CNM stands for Container Networking Model. It is a standard or specification from Docker, Inc. that forms the basis of container networking in a Docker environment. This docker's approach provides container networking with support for multiple network drivers.

27. Does Docker offer support for IPV6?

Yes, Docker provides support IPv6. IPv6 networking is supported only on Docker daemons runs on Linux hosts. However, if you want to enable IPv6 support in the Docker daemon, you need to modify /etc/docker/daemon.json and set the ipv6 key to true.

28. Can you lose data when the container exits?

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

29. What are a different kind of volume mount types available in Docker?

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

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

To configure the Docker daemon to default to a specific logging driver. You need to set the value of log-driver to the name of the logging drive the daemon.jason.fie.

Career scopes and salary scale

There are many companies who are looking to hire individuals who have the expertise and knowledge about docker engine programming systems. As most of the application hosts require Docker Engine setups, it’s quite important to know that these hirers look forward to those individuals who are not only well-versed with the application but also know how to handle the pressure. Therefore, if you think that you have the right expertise and skill to become a docker engine programmer, then it’s the right time for you to start giving interviews in the companies. As a fresher, you have the scope to earn about 138,017 dollars per annum, and if you are experienced, then you can earn up to 230,000 dollars per annum

Conclusion

When it comes to giving interviews and cracking it with flying colors, then you can use our Docker interview questions and answers that are prepared by our experts and professionals. You can also drop us a message to clarify your doubts or queries.

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