Prepping for an interview is one of the toughest parts. And that’s because you don’t really know what the interviewer will end up asking you. You may have read up all possible information, but are you really prepared for the volley of questions you will be facing in your interview?
The same applies to Docker interviews. Docker took the IT industry by storm early in 2013. And it’s still trending just as much, which means it brings a whole lot of scope for new jobs. If you have applied for the job, the next step is to prepare as much as you can for the interview. To make your job easier, we’ve compiled a list of 15 most asked Docker interview questions. So, let’s get started with them right away:
1. What is Docker?
ANS. Since this is a Docker interview, the possibility of you being asked this question is really high. While you may have studied Docker in-depth, at this point, you have to give a brief, concise definition of Docker. You can start by saying:
Docker is a comprehensive open-source, lightweight containerization technology. It packages your application and all its dependencies and has gained immense popularity in the cloud and application packaging world. Docker containers can wrap basically anything that can be installed on a server. With the help of these lightweight, portable containers, Docker helps automate the deployment of applications.
2. What are the major advantages of Docker?
ANS. Docker is extremely efficient and has a super easy setup process. With the help of Docker, you can easily describe the entire lifecycle of your application in detail. This documentation is comprehensive and provides every tiny detail of application information. On an overall basis, Docker boosts the overall operational efficacy, greatly enhancing the productivity of your organization.
3. What is Containerization?
ANS. The whole and soul of Docker is the container mechanism, which means you can expect this question in your interview. To answer this question, you can simply go ahead with a crisp, clear, and precise answer:
Containerization is a lightweight alternative to full machine virtualization. It involves the encapsulation of an application in a container with its own operating environment. One of the many benefits of loading an application onto a virtual machine is that it can be run on any suitable physical machine without worrying about any kind of dependencies.
4. What is Virtualization?
ANS. The method of strategically dividing mini-frames is known as virtualization. Virtualization allows you to run multiple applications simultaneously, without any glitches. A software called Hypervisor facilitates this splitting, and the virtual environment created by the Hypervisor is called the Virtual Machine.
5. State the difference between Containerization and Virtualization.
ANS. Once you have defined Containerization and Virtualization, stating the difference between both concepts should not be difficult. However, to put it forth briefly, you can choose to say:
The container offers you an isolated environment required to run the application. In containerization, the entire user space is wholly dedicated to the application itself. On the other hand, in virtualization, the Hypervisors provide access to an entire virtual machine to the guest.
6. What are Docker Images?
ANS. Docker images are the source of Docker containers. It is a read-only template that contains a set of instructions for creating another container that can run on the Docker platform. It is the most convenient way to package applications and preconfigured server environments into Docker containers. This can be used privately or can be shared publicly with other Docker uses, and that is completely your choice.
7. What is a Dockerfile?
ANS. A Dockerfile is a configuration file that helps automate the steps of creating a Docker image. Docker picks the instructions in the Dockerfile and begins the process of creating a Docker image by itself. A Dockerfile speeds up the process of creating a Docker image, which would otherwise be time-consuming if done manually.
8. What is a Docker Engine?
ANS. Docker Engine, also known as the Docker Daemon represents the server. It supports the tasks and workflow involved to build, ship, and run container-based applications. The engine provides a CLI (Client Line Interface), enabling users to interact with the daemon through the Docker Engine API.
9. What is a Docker Swarm?
ANS. Native clustering for Docker is termed as Docker Swarm. This swarm turns a pool of Docker hosts into a single, virtual Docker host. Any tool that already communicates with the Docker daemon can leverage the Docker Swarm to instantly and transparently scale multiple hosts.
10. Describe Docker Compose
ANS. A YAML file, Docker Compose contains details about services, networks, and volumes for setting up the Docker application. Using the Docker Compose, you can create separate containers and host them. Not only this, but Docker Compose also doubles up as the link of communication between them.
11. What is Docker Hub?
ANS. Docker hub is a cloud-based registry. Docker hub helps you to link to the code repositories, allowing you to build, test, and store your image on the Docker Cloud. It also helps you deploy the image to your host, facilitating a seamless transfer.
12. How is Docker different from other methods of containerization?
ANS. In Docker, the containers can be easily deployed in any cloud platform. As compared to other containerization technologies, Docker allows you to seamlessly run multiple applications on the same hardware simultaneously. Developer-friendly, Docker can quickly create ready-to-run containerized applications, making the whole process of managing and deploying applications a lot easier.
13. How many containers can run per host?
ANS. There is no limitation on the number of containers per host. Docker gives you the flexibility of as many containers on a given host. Containers are extremely lightweight, but you cannot deny the fact that they are heavily dependent on the host OS. This means we need to consider different aspects such as memory, CPU, and memory, as the number of hosting capability is completely dependent on it.
14. What platforms does Docker run on?
ANS. Docker runs on various Linux administrations, such as Gentoo and Archlinux among others. It is also compatible with Cloud platforms such as Google Compute Engine and Rackspace.
15. Will Docker replace Cloud technology?
ANS. Docker and Cloud have different strengths of their own. Even though the popularity of Docker is increasing, Cloud too, has amped up the game with its range of new features. Despite all this, Docker will never be replaced by the Cloud. In fact, organizations should be in a position to leverage the best of both Docker and Cloud for their benefit.
We hope these Docker interview questions and answers will help you cruise through your interview easily!