11/Jul/2020 | 10 minutes to read
QFLES is listing some Essential Docker Interview Questions and Answers for Freshers and mid level of Experienced Professionals prepared by Industry Experts. All answers for these Docker interview questions are given based on standard documents and tried to explain in simple and easiest way.
1. What is the Docker?
Docker is an open-source Platform that provides the capability to develop, test, ship and run your application in an isolated environment. This isolated
environment is called container. Docker enables you to keep your application separate from your Infrastructure and it reduce the delay between developing your application and deploy
it in production.
Docker run the applications in an isolation with security, it allows you to run many containers on a host machine (A machine where many virtual machines are created and run). Containers are light weighted as they directly run within host machines's kernel rather than running on hypervisor (It's a system that creates and runs virtual machines). It means you can run more containers on this hardware than if you were using virtual machines. Even you can run docker containers on virtual machines as well.
Docker Certified Associate (DCA) exam is designed by Docker to validate the skills
2. What is the Docker Engine?
Docker Engine is an application which has client-server type architecture with these major components.
3. What can you use Docker for?
You can use the docker for:
4. Give some Docker Example scenarios.
As Docker provides the consistent and fast delivery of applications, these are the below examples for that.
5. Explain the Docker architecture.
Docker is based on client-server architecture. Docker client talks to docker daemon (A long running program) via REST API over a network interface or UNIX sockets.
Docker client and daemon can run on same system or remote. Docker daemon is responsible for building, running and distributing the containers.
Source: Docker Architecture
6. What is DTR (Docker Trusted Registry)?
If you are using Docker Data Center (DDC), then Docker provide enterprise grade image storage solution called Docker Trusted Registry (DTR). DTR can be installed on virtual private network or on-premises so that you can store your images in a secure way and behind your firewall. DTR also provides a User Interface that can be accessed by authorized users to view and manage the repositories.
7. What are the common Docker objects?
With Docker you use many things like Images, Containers, Registries, Services, Volumes etc. These all are Docker objects.
8. Explain the Docker Images.
An Image is a read-only template with instructions that forms the basis of a container. It's an order collection of file-system changes. Image is based on
another image with some customizations. for example, you can create an image that is based on 'ubuntu' image but you can install other application dependencies.
Images contains a set of run parameters (starting executable file) that will run when container starts.
9. Why Images are light weight, fast and small?
Docker allow you to create your own image using a docker file with simple instructions needed to create an image. Each instruction create layers in docker image. So when you make any changes in docker file then only changed layers are rebuilt not all, this is the reason that docker images are fast, small and light weight in compare to other virtualization systems.
10. Describe Docker Containers?
Containers are created from Images or you can say Container is a runnable instance of an image. When you build your image and deploy the application with all the dependencies then multiple containers can be instantiated. Each container is isolated from one another and from host machine as well. So A Container is defined by an image and other configurations provided when you start or create it.
11. Explain the underlying technology of Docker.
Docker is developed in Go Language and has capability to use many Linux kernel features to deliver the functionality. Docker is also relies on many other below technologies as well.
Docker Quick Facts:
Docker is being popular with the time and here is what you should know about docker.
Future of Docker:
Docker offers a quick way to build, develop, ship and orchestrate the distributed applications in isolated environment.
Docker is being used by many companies to make developer's process faster. Docker also provide automatic deployment management. So Mostly companies are adopting this containerized approach for their application development and deployment.
Docker also provide integration with many hundreds of tools like Bitbucket, Jenkins, Kubernetes, Ansible, Amazon EC2 etc. So there are lot of jobs in the market for Docker skills and Docker Professionals are being paid very good salary.
Some General Interview Questions for Docker:
1. How much will you rate your self in Docker?
When you attend an interview, Interviewer may ask you to rate your self in specific Technology like Docker, So It's depend on your knowledge and work experience in Docker.
2. What challenges did you face while working on Docker?
This question may be specific to your technology and completely depends on your past work experience. So you need to just explain the challenges you faced related to Docker in your Project.
3. What was your role in last Project related to Docker?
It's based on your role and responsibilities assigned to you and what functionality you implemented using Docker in your project. This question is generally asked in every interview.
4. How much experience do you have in Docker?
Here you can tell about your overall work experience on Docker.
5. Have you done any Docker Certification or Training?
It's depend on candidate like you have done any Docker training or certification. Certifications or trainings are not essential but good to have.
Conclusion:We have covered some frequently asked Docker Interview Questions and Answers to help you for your Interview. All these Essential Docker Interview Questions are targeted for mid level of experienced Professionals and freshers.