Docker Interview Questions and Answers

Hypervisor refers to software which has a tendency to make virtualizations possible and it is also known as virtual machine monitor. The hypervisor also segments the host system by allocating the resources to the individual virtual environment. With this utility, the user can have various operating systems on a single host system.

Type of hypervisors are-

• Type 1: It is known as a native hypervisor or bare-metal hypervisor which runs directly under the host system.
• Type 2: It utilizes the underlying host operating system it is also known as a hosted hypervisor.

Note: As we are going through Docker interview questions and answers it is very important to have a brief over what is Docker.

Docker presents a containerization platform packaging applications along with its dependencies together in a container form. It is yours that the applications work seamlessly under any environment (no matter if it is a test, development of production). The Docker containers wrap the piece of software in an entire file system containing the essentials like code, runtime, system libraries, system tools and many more. It also wraps everything which is installed on a server guaranteeing its run time regardless of the environment.

The lifecycle of a Docker is as follows-

• Create a container
• Run the Docker container
• Pause container
• Unpause container
• Start container
• Stop container
• Restart container
• Kill container
• Destroy container

The application and its dependencies are included in Docker containers. It can also share the kernel with various other containers running on individual processes in user space on any of the host operating systems. These containers are not bound to any defined specific infrastructure or any computer or infrastructure. They are compatible with the cloud and runtime instances of images.

A docker image is the fundamental source of Docker container it is better to say that they are used to create the Docker containers. When the user runs these images corresponding instance for the container is developed automatically in it. These images can be used for any other Docker environment as well.

Virtualization is a process of creating the virtual session of computer storage, service or applications which are software-based. This virtual environment is created from a single segment of the physical hardware system and through it, you can split one system into various other sections acting like a separate and distinguishable system. With the help of hypervisor, this splitting is executable and the virtual session created by this medium is known as a virtual machine.

The Docker architecture majorly consists of an engine which refers to a client-server application having three major components, these components are-

• A server which represents the long-running program type known as a daemon process (Docker command)
• A REST API which defines the interface used in the program to talk to the daemon and then follow the instructions
• A command-line interface client
• CLI utilizes the Docker REST API to organize or control Damon with scripting or direct commands.

It is justified in Docker that the containers are made up of Docker images. These Docker images are defined in a separate registry which is known as Docker Hub. From this defined registry it is easy for the users to pick images and use them to create containers and customized images. At present Docker Hub is the world's largest public repository for image containers.

Docker objects: The Docker objects refer to the Docker images, containers and services. A Docker image is a read-only template having the configuration and runtime instructions for Docker instructions. Under the service instruction scaling of the containers across multiple Docker, daemons are allowed. All this together works as Swarm.

Docker namespaces: It refers to a technology that provides individual and isolated workspaces known as containers. Docker namespaces also provide a layer of isolation for containers.

The most important commands in Docker are-

• Docker- It is used to launch the Docker daemon
• Build- It is used to build image files in Docker
• Create- It is used to create a new container
• Kill- It is used to kill the container
• Commit- It is used to create a new image from the container modifications.