Docker and Kubernetes Interview Questions


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Kubernetes, is an open-source orchestration software that makes it possible to control where and how containers run. It lets you run Docker containers and other workloads. Additionally, it helps you deal with some of the operational complexities involved in scaling multiple containers across multiple servers. Kubernetes allows you to manage a cluster of virtual machines and schedule containers for those virtual machines according to their compute resources and the resource needs of each container.

Kubernetes’ basic operational unit is the pod. Containers can be grouped together into pods. These pods and containers can be scaled to any desired state. You can also manage their lifecycle to ensure your apps are always up and running. This article contains questions about Kubernetes and Docker that will help you prepare for any certification or interview you might need after you have completed your Kubernetes training. So let’s get to it.

Docker and Kubernetes Interview Questions 

1. What is Kubernetes?

This is one the most important Kubernetes interview question, but also one of its most crucial. Kubernetes, an open-source container orchestration system or tool, automates tasks such as scaling, monitoring, scaling, and managing containerized applications. It can manage multiple containers easily (since it can handle groupings of containers), which allows for logical units to be discovered and managed.

2. What is a K8?

Kubernetes are also known as K8s.

3. What is orchestration in software development and DevOps?

Orchestration is the integration of multiple services to allow them to automate processes and synchronize information quickly. For example, let’s say you have six to seven microservices that an application needs. You could create communication problems if you placed them in different containers. Orchestration can help with this situation. It allows all services to work together seamlessly to achieve a single goal.

4. What is Kube-proxy?

Kubeproxy acts both as a load balancer and network proxy that supports service abstraction. Kube-proxy directs traffic to the correct container based upon IP and port number. Kube-proxy directs traffic to the correct container based upon IP and port number.

5. What is a load balancer in Kubernetes, and what do you know about it?

One of the most popular and common ways to expose service is through a load balancer. Based on the environment in which they are used, there are two types. Depending on the working environment, either the External Load Balancing or the Internal Load Balancing is used. The Internal Load Balancing automatically balances load and assigns pods with the appropriate configuration, while the External Load Balancing directs traffic from external load to backend pods.

6. What is orchestration in software?

App orchestration is the ability to integrate multiple applications into one software process. Automated management, coordination, and arrangement of computer software will be possible. Any orchestration process should aim to optimize repeatable, efficient processes.

7. What does a pod mean in Kubernetes?

A Kubernetes pod can be described as a collection of containers running on the same host. If we deploy single containers regularly, our pod and container will be the same.

8. What does Kubernetes mean by a node?

Kubernetes nodes are worker machines, also known as minions. A node could be either a virtual or physical machine. Each node has a service that runs pods. It is managed by master parts. These node services can include kubelet and kube-proxy.

9. What is a Heapster, and how do they work?

The Heapster allows us to monitor container clusters. It allows us to do cluster-wide monitoring as well as event data aggregation. It supports Kubernetes natively.

10. How do you write a Kubernetes Scheduler?

Kubernetes default scheduler is the kube-scheduler. You can also create your own scheduler and use it instead. In scheduling life cycle:

  • A pod is created, the preferred state is specified, and it is saved to etcd.
  • The scheduler sees that the new pod has no node bound
  • It locates a suitable node to host that pod
  • The API server is notified to bind the pod to the node. Next, the desired state is saved at etcd.
  • Kubelets monitor the bound pods and open the containers at the appropriate node.

11. What are the best ways to implement API Security on Kubernetes

Here are some ways API Security can be provided:

  • Use the correct auth mode when authenticating with API server: Node, RBAC
  • Ensuring traffic protection by TLS
  • Using API authentication
  • Ensuring that kubeless protects its API via authorization-mode=Webhook
  • Monitoring RBAC failures
  • Removing default service account permissions
  • Ensuring that the Kube-dashboard follows a restricted RBAC policy
  • Implementing a pod security strategy for container restrictions and protection of the node
  • Use the most recent version of Kube

12. What is Docker?

Docker is an open-source lightweight containerization technology. It is a popular choice in the cloud and application packaging industry. It makes it possible to automate application deployment in portable and lightweight containers.

13. What is a docker image?

These executable packages are bundles of software packages and application code. They are used to create containers. Docker images can easily be deployed to any docker container environment. The containers can then be spun up to run the application.

14. What can you tell us about Docker Compose?

It’s a YAML file that contains all details about various services, networks, and volumes required to set up the Docker-based app. Docker-compose can be used to create multiple containers, host them, and establish communication between them. Ports are exposed on every container for communication between containers.

15. Do you have any information about the docker namespace?

Namespaces are basically Linux features that allow OS resources to be partitioned in a mutually exclusive fashion. Namespaces are the heart of containerization. They provide a layer for isolation between containers. Namespaces in docker ensure that containers can be moved and don’t impact the host. Docker currently supports the following namespace types: PID, Mount, User, Network, and IPC.

16. What is Hypervisor?

Hypervisor software makes virtualization possible. It’s also known as Virtual Machine Monitor. It divides the host and assigns resources to each virtual environment. It is possible to have multiple OS running on one host system. There are two types of Hypervisors.

Type 1: Also known as Native Hypervisor, Bare metal Hypervisor. It is directly connected to the host system. It is able to access the hardware of your host system and does not require a base operating system.

Type 2: This type of hypervisor uses the underlying host operating systems. This is also known as Hosted Hypervisor.

17. What is virtualization?

Virtualization refers to the creation of a software-based virtual version of something (compute storage, servers, and applications, etc.). These virtual environments or versions are made from one physical hardware system. Virtualization allows you to split a system into multiple sections that act as distinct systems. This is possible with Hypervisor software. Virtual Machine is the name of the virtual environment created using a hypervisor.

18. What is containerization?

Let me give you an example to illustrate this. Software development can sometimes lead to code that is not compatible with another machine’s version of the software. The containerization concept solved this problem. The containerization concept basically means that an application is packaged and wrapped with all its configuration files, dependencies, and other information. This bundle is known as a container. The container can be deployed to another system to allow for bug-free operation. All dependencies and libraries have been wrapped together. Kubernetes and Docker are the most well-known containerization environments.

19. What is the difference between virtualization and containerization ?

After you have explained virtualization and containerization, the next question is about differences. This could be about virtualization and containerization, or between virtual machines and virtual containers. This is how you answer.

Containers offer a separate environment to run the application. The application is the only user space. Any changes made within the container are not reflected on the host or any other containers that may be running on the same host. Containers represent an abstraction of the application layer. Each container represents a different application.

Hypervisors in Virtualization provide a complete virtual machine to the guest (including Kernal). Virtual machines represent an abstraction of the hardware layer. Each VM is a physical device.

20. What is the relationship between Kubernetes & Docker?

This is the most frequent Kubernetes interview question. The interviewer may ask you to tell the interviewer about your experiences working with any of these platforms. Docker is an open-source platform that allows software developers to develop. Its primary benefit is that it bundles the settings and dependencies of the software/application into a container. This allows for portability, as well as other benefits. Kubernetes can be used to manually link and orchestrate multiple containers that are running on multiple hosts.

21. What are the key differences between Kubernetes and Docker Swarm?

Docker Swarm, Docker’s native open-source container orchestration platform, is used to schedule and cluster Docker containers. Swarm is different from Kubernetes in these ways:

  • Docker Swarm is easier to set up but does not have a strong cluster. Kubernetes, on the other hand, is more difficult to set up but has the advantage of having a stable cluster.
  • Docker Swarm cannot do auto-scaling like Kubernetes. However, Docker scaling can scale five times faster than Kubernetes.
  • Docker Swarm does not have a GUI. Kubernetes does, however, provide a GUI in the form of a dashboard
  • Docker Swarm automatically balances traffic between containers within a cluster. Kubernetes, however, requires manual intervention to balance such traffic.
  • Docker uses third-party tools such as ELK stack to log and monitor, but Kubernetes integrates tools for the same.
  • Docker Swarm lets you share storage volumes easily with any container, while Kubernetes cannot share storage volumes with containers within the same pod.
  • Docker allows rolling updates to be deployed, but not automatic rollbacks. Kubernetes, however, can deploy rolling updates as well as automatic rollbacks.

Final Thoughts

Understanding of DevOps and on-premises Software Development is a great way to gain a holistic perspective of the subject. The best way to prepare for the interview is to use the Docker and Kubernetes interview questions you have learned. These types of Kubernetes interview questions will help you to demonstrate your knowledge and skills.

Kubernetes and Docker collaborate. Docker is an open standard that allows you to package and distribute containerized applications. Docker allows you to build, run and share containers. Although Docker can be run on Kubernetes, it is not the only solution. To optimize Kubernetes in production, implement additional tools and services to manage security, governance, identity, and access along with continuous integration/continuous deployment (CI/CD) workflows and other DevOps practices.


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