DevOps Interview Questions

Today DevOps is considered to be the latest buzzword in the market due to immense benefits offered and how it has changed the SDLC process. Unlike the traditional software development approach like Agile, DevOps majorly focuses on the collaboration of the development and the operational teams. As it has been widely adopted by many organizations in the last few years, it has led to the rise in the demand for DevOps engineers for managing and improving the software development process.

If you are looking for DevOps engineer roles then you need to understand its concept, required skills, resources, and various points so you can excel in implementing the DevOps approach. In this article, we will be highlighting the most frequently asked DevOps questions that are suitable for interviews.

Introduction to DevOps.

DevOps is a software development methodology that is considered as the combination of development and operations. It is an extension of the Agile methodology with its focus on bringing together various teams together for developing the product. It emphasizes team collaboration for improving the productivity and performance of the team members. This approach helps in automating the various processes of software development for delivering an efficient and high-quality product. It allows the team to deliver the product faster and resolve the issues at the early stage by getting feedback from customers.

How is DevOps different from Agile Methodology?

Agile is the conventional approach that was used for all software development. It focuses on the iterative, incremental, and rapid software releases along with getting feedback from the customers on each iteration. It helps in bridging the gap between the customer and the developer.

While you can say that DevOps is an advanced version of Agile, its main focus is on increasing communication with the team for better productivity. Various teams come together for continuous development, testing, deployment, and monitoring of the SDLC pipeline. The main objective of DevOps is to set equal responsibilities for the development and the operational team to eliminate the conflict between them so they can work for the improvement of the product.

Explain different Phases of DevOps.

DevOps has various phases as explained below.

Plan- first step is to set up a plan for what type of application needs to be developed and to create a rough picture of how the development will take place.
Code- at this phase, the development team works on code as per the client’s requirement.
Build- at this phase, various codes are integrated to create an application.
Test- it is considered to be the crucial stage where we look for possible bottlenecks and try to eliminate them and rework some parts if required.
Integrate- at this phase, we merge the codes from various developers in the team to merge functionalities.
Deploy- now, the code is ready to be deployed on the desired environment.
Operate- In this phase post deployment, developers can make changes as per the changing demand.
Monitor- at this stage, teams monitor the performance of the application and make the required changes to make it more efficient.

Mention the Benefits of DevOps

We have mentioned some of the benefits of DevOps.

It ensures faster software deployment.
It helps in stabilizing the work environment.
This methodology will improve the quality of the product.
It allows automating various tasks of the software development lifecycle to eliminate manual work.
It helps in promoting agility within your business.
It reduces the failure and production cost for every business.
It helps in frequent releases with new features, fixes, and updates.
It focuses on team collaboration for better productivity.
It results in customer satisfaction by providing a high-quality product.

Explain the difference between continuous delivery and continuous deployment?

Continuous Delivery	Continuous Deployment
It focuses on the code to be safely deployed to the production environment.	It ensures that each change will pass the automated tests to be deployed to production automatically.
It makes sure that the business applications and services will function as expected.	It helps in making the software development and the release process faster.
It helps in delivering every change to a production-like environment via rigorous automated testing.	There is no need for approval from a developer for making changes.

Explain the role of Continuous Management in DevOps.

Below are some roles of continuous management in DevOps.

Disaster recovery- with the help of continuous management, you will be able to recover your assets during any disaster. It allows you to roll back the changes if it breaks down the application and go back to the state before the change.
Uptime and Site reliability- with continuous management, you will be able to manage the downtime and site reliability. It makes sure that there is minimum downtime due to deployment errors.
Easier scaling- with the help of configuration management, you can evaluate the state of your services. It also allows you to scale them as per the changing request / demand without any failure.

Explain the Role of Continuous Monitoring.

DevOps supports continuous monitoring which helps in detecting, identifying, and reporting any error in the entire infrastructure. It helps in ensuring that all the services and applications are running efficiently on the servers. Itl monitors the status of the server. It also conducts continuous auditing of the system to make the required changes.

Explain Continuous Integration in DevOps.

Continuous Integration is a DevOps practice that allows the developers to integrate their code into a shared repository. All integration is verified using the automated build process for easy error detection in their codes. Having a repository allows the developers to check their code and work on the features assigned to them. After working on the code, they are pushed to the remote shared repository which is handled by effective version control tools like Git. The CI server monitors the changes and pulls them as soon as it detects them. After pulling the changes, the CI server will trigger the code build for running tests. The results of the tests are sent to teams so that they can rework in case of failure.

Explain Continuous Testing in DevOps.

DevOps supports continuous testing that allows the teams to run automated test cases to get immediate feedback on the product quality and for validating the business risks that are associated with the automated code builds. This phase enables the team to test each build continuously to give instant feedback to the developer team so that these changes will not reach the later stages of development. This leads to the efficient development and testing process to create a high-quality product.

Explain the Benefits of Automation testing.

Test automation helps in improving the overall efficiency and quality of the software. You can use specific tools for effectively executing automated test cases and then comparing actual and expected results. Thus, test automation ensures software proficiency without any manual intervention. Below we have mentioned the benefits of the automation testing process.

It helps in getting faster feedback to make any required changes to the code. Then the change is tested using automated test cases.
It helps in saving the time spent by the team in repeatedly validating the new features.
It helps in improving the team communication so they can work closely with the development and deployment of the test cases.

How to Automate Testing in DevOps?

In DevOps, developers commit all the changes made in the source code to a shared repository. Then Continuous Integration tools like Jenkins pushes the changed code from this shared repository and deploy it for Continuous Testing using tools like Selenium. It allows testing every code change continuously.

What are the Principles of DevOps?

You must understand the basic principles of DevOps before implementing them within your organization. Below we have mentioned some DevOps principles for better understanding.

It focuses on team collaboration for improving the productivity and performance of various teams.
It sets the same responsibilities for various teams so they can focus towards the development and improvement of the product by eliminating the chance of blame game.
It focuses on minimizing the cost of failure as it ensures continuous development, testing, and management.
It focuses on automating every task and process within the organization for effective working.
It works mainly for the improvement of the product.

Version control system- DevOps interview questions

Explain Version Control.

It is a system that helps in recording the changes to files or code so that you can refer to a specific version in the future. It has a central shared repository that is used by the teammates for committing desired changes to the file. Version control helps the team to revert the entire project to its previous stage before the change was implemented. It allows you to compare the changes over time. Using version control, you will be able to know who made the last changes and what impact they had on the system.

Explain the Benefits of Version Control.

Below are some benefits that you will get using the Version control.

Version control system (VCS) allows the team to work and make changes to any file at any time. Later, you can merge all the changes in a single version.
Every version is efficiently stored at the VCS and you can request any of the stored versions and you can implement that version to your system instantly.
While saving any version, you can provide a name describing what change has been made to it. So that any developer can refer to it to see the desired changes.

What are the Branching Strategies in VCS?

You can use any of the below-mentioned branching strategies in VCS.

Feature branching- this type of branching will keep all the changes related to a specific feature inside a branch. Once the feature is completely validated and tested then it is merged to the main branch.
Task branching- this type of branching allows implementing each task in its branch along with the task key. You can look for the task key to see which code implemented which task.
Release branching- as soon as the develop branch gets all the required features to be released, then you can create a clone of that branch to form a release branch. You are not allied to add new features after this point.

What is Git?

Git is one of the majorly used Distributed Version Control systems (DVCS). It allows the team to track changes made to a file and then revert to any specific changes.
It is usually preferred over other Version Control Systems (VCS) like SVN as Git does not rely on a central server to keep all the versions of a project’s files. Instead, every developer creates “clones” of a repository with “Local repository” and keeps the complete history of the project on the local system that can be referred to when there is a server outage. For complete recovery, you can access your teammate’s local Git repository.
It comes with a central cloud repository where developers can commit the required changes and share it with other developers where all collaborators are making changes “Remote repository”.

Containerization-DevOps questions

Explain Docker.

Docker is an open-source project that allows you to create containers and container-based applications. It was designed for Linux systems but now can also be used on Windows and Mac systems. Docker enables you to create independent applications that do not rely on the underlying infrastructure. Docker allows you to manage the infrastructure as you manage your applications. It eliminates the delay between writing code and running it in the production environment.

Explain Docker Architecture.

Docker is based on the client-server architecture.
Docker Client is a service that will run a command which gets translated using the REST API and then sent to the Docker Daemon (server).
Docker Daemon receives the request and communicates with the operating system for building the Docker images and running Docker containers.
A Docker image specifies a template holding various instructions for creating containers.
Docker container is an executable package that consists of an application along with its dependencies bundled together.
Docker registry is a service that will help in hosting and distributing Docker images among users.

Explain the Benefits of Docker.

Below are various benefits of Docker.

It provides a consistent and isolated environment for running applications or containerized applications independently without relying on the underlying infrastructure. You can deploy your applications anywhere.
It helps in faster deployments as you can run containerized applications independently. As these applications are bundled with their dependencies so they will not take time to look for the dependencies elsewhere.
It helps in easy maintenance as each container is isolated from the other, allowing teams to troubleshoot easily with quick fixes.

Name Docker tools for CI/CD.

Continuous Integration/Continuous Deployment (CI/CD) (10)

Jenkins
Circle CI
CodeShip
GitLab CI
Shippable
CodeFresh
Travis CI
Buddy
Drone
Wrecker

Name Docker tools for Continuous monitoring

Sumologic
Retrace
Datadog
New Relic
cAdvisor
Pagerduty

Why is Docker so popular?

Docker works faster and more reliably than a Virtual machine.
Docker is portable due to the consistency of the host environment irrespective of the underlying OS.
Docker works on Containerized applications that can be efficiently scaled up or scaled down with changing business requirements.
Using the Container concept, the complex application can be easily broken down into modular microservices.
Docker ensures a faster way for deploying applications without focusing on the deployed platform.
Docker comes with seamless integration with the DevOps development and deployment cycle.

What are the Key elements of Continuous Testing tools?

Key elements of Continuous Testing are:

Risk Assessment: It helps in conducting risk mitigation tasks, technical debt, quality assessment, and test coverage optimization for ensuring that the build is ready to move to the next stage.
Policy Analysis: It ensures all processes adhere to the organization’s evolving business and compliance demands.
Requirements Traceability: It ensures that all the desired requirements are met without any rework. An object assessment identifies if any requirements are at risk, working as expected or not, or require further validation.
Advanced Analysis: It uses automation for static code analysis, changes impact analysis and scope assessment for eliminating defects in the first place
Test Optimization: It ensures tests provide accurate results.

Explain the usage of the Docker file.

Using Dockerfile, you will be able to create Docker images using the build command.
With a Docker image, you will be able to run the code for creating the Docker containers.
Once a Docker image is built, it will get uploaded to a Docker registry.
From the Docker registry, anybody can download the Docker image and build a new container whenever required.

Difference between Docker image and Docker container.

Docker Images	Docker Container
Docker images can be used as a template of Docker containers	Containers are considered to be runtime instances of a Docker image
Any user can create an image using a Dockerfile	You can create Containers using Docker images
You can find an image in the Docker repository or a Docker hub	You can find the container in the Docker daemon
The Docker image layer is a read-only filesystem	Every Docker container layer is a read-write filesystem

Creating a Docker Container.

A user can either create a new Docker image or can pull an existing Docker image (like Apache) from Docker Hub (official Docker repository).

Now, you can use Docker for creating a new Container Apache using the existing Docker image. At the same time, the container layer of the read-write filesystem will also get created on top of the image layer. You can run the below-mentioned commands.

Command for creating a Docker container: Docker run -t –i Apache
The command for listing down all the running containers: Docker ps

Difference between Registry and Repository.

Registry	Repository
A Docker registry is available as an open-source server-side service that is usually used for hosting and distributing Docker images.	It is a collection of several versions of Docker images
Users will be able to distinguish between Docker images with their tag names that are available in the registry.	It is stored in a Docker registry
Docker comes with its default registry known as Docker Hub.	There are two types of repositories: public and private

What are Common Myths about DevOps?

There are various myths being talked about DevOps.

According to some, DevOps replaces Agile. It is not true as DevOps is an extension of Agile, combining all the features of Agile with team collaboration.
The implementation of DevOps may vary depending on the project requirements. Although it is partly true, it is recommended to follow standard procedure so there will be no issues when you move your project from one company to another.
The assumption that DevOps is only about automation is not entirely correct. DevOps is a methodology that incorporates various practices such as collaboration, CI/CD, and continuous testing, which need to be understood before implementation.
Automating software development could solve all problems, but this is not feasible over the long term. In the absence of human intervention, the errors of one stage will create bottlenecks for the next stage if they are not corrected early on.
You can use DevOps to manage not only complex business requirements but also large and complex infrastructures with the correct DevOps implementation.

Mention Challenges of DevOps.

Below are some challenges that you might face using the DevOps approach.

You may face compatibility issues if you are working on legacy systems and creating an application in them.
For implementing the DevOps approach, we need skilled and experienced people that can effortlessly maintain the standards. But there are very few people who are cross-skilled and suitable for a DevOps engineer.
Though you will get various tools for implementing DevOps, choosing the right one is critical that meets all the business requirements.

Explain the Role of AWS in DevOps.

AWS has the following role in DevOps:

Flexible services – it helps in providing ready-to-use, flexible services without installing or setting up the software.
Built for scale – it allows you to manage a single or scale to thousands of instances.
Automation – it helps in automating various tasks and processes, allowing developers to focus on innovation.
Secure – AWS offers Identity and Access Management (IAM) for setting user permissions and policies.
Large partner ecosystem – AWS comes with a support for the large ecosystem of partners that can be easily integrated with other AWS services.

Explain “Infrastructure as Code” related to Configuration management.

Writing code for managing configuration, deployment, and automatic provisioning.
It allows you to manage the data centers with machine-readable definition files, instead of physical hardware configuration.
It makes sure that all your servers and other components of the infrastructure are provisioned consistently and effortlessly.
It allows you to administer the cloud computing environments, also known as infrastructure as a service (IaaS).

Mention Prerequisites for Implementing DevOps.

You should maintain the below-mentioned prerequisites.

You should have at least one Version Control Software
Ensure effective communication among various team members
Ensures tools for implementing automated testing
You should have the right tools for automated deployment.

Mention Network Monitoring tools for DevOps.

Some of the most commonly used network monitoring tools are:

Splunk
Icinga 2
Wireshark
Nagios
OpenNMS

Name Important KPIs of DevOps.

Below are the three most important KPIs of DevOps.

Mean time to failure recovery
Frequency of the Deployment
Percentage of failed deployments
Application usage, performance, and traffic
Automated Test Case Pass Percentage.
Application Availability
Change volume requests
Customer tickets

Explain CBD in DevOps.

CBD stands for component-based development, a unique approach to creating a product. With this approach, developers can reuse the existing well-defined, tested components of the code and save time and effort by not having to create the application from scratch.

Explain Post Mortem meetings in DevOps.

Post mortems are meetings held by various team members to discuss if anything goes wrong or fails during the implementation of the DevOps approach. This meeting will primarily focus on finding a solution to avoid similar failures in the future and understanding the cause of those failures.

Explain the Container.

Containers can be defined as packaged applications that bundle their dependencies together in a single file. The containers that fall into this category can run on any platform, regardless of the underlying operating system. They share the same kernel with other containers that run on the same platform. Docker is one of the most commonly used containerized platforms allowing you to create, manage, and run containerized applications on any platform.

Explain Docker Hub.

Docker hub is the cloud-based registry service that links you to the repository where you will be able to build images, test them, store the pushed images (manually), and links you to the Docker cloud for deploying the images to the host. It is a centralized resource for container image discovery, distribution.

Name some DevOps popular tools.

Git: Version Control System tool
Jenkins: Continuous Integration tool
Selenium: Continuous Testing tool
Puppet, Chef, Ansible: Configuration Management and Deployment tools
Nagios: Continuous Monitoring tool
Docker: Containerization tool

Mention success factors for Continuous Integration.

It helps in maintaining a code repository
It allows you to automate the build
It helps in making the build self-testing
It allows the team members to commit to the baseline every day
It ensures to keep the build fast
It helps in making it efficient to get the latest deliverables
It helps in automating the deployment

Explain the benefits of Containerization over Virtualization.

Below are some advantages of containerization versus virtualization:

Containers offer real-time provisioning and scalability while the VMs provide comparatively slow provisioning.
Containers are lightweight as compared to the VMs
VMs comes with a limited performance as compared to containers
Containers show better utilization of the resources as compared to VMs

How to start and stop Docker Containers?

For stopping the Docker container run the below command: docker stop <container ID>
For restarting the Docker container run the below command: docker restart <container ID>

Mention platforms where you can run Docker.

Here, we have mentioned Linux and Cloud platforms as they are widely used.

Linux

Ubuntu 12.04, 13.04 et al
Fedora 19/20+
RHEL 6.5+
CentOS 6+
Gentoo
ArchLinux
OpenSUSE 12.3+
CRUX 3.0+

Cloud:

Amazon EC2
Google Compute Engine
Microsoft Azure
Rackspace

Explain Resilience Testing.

It is a software testing process that tests applications to see how they behave under uncontrolled circumstances. In addition, it ensures that the data and functionality of the application remain intact under those conditions.

Explain the DevOps approach for Creating a Project.

You can use the following DevOps approach for creating a project.

Stage 1: Plan: Analyze the existing processes to identify areas that could be improved, as well as blind spots, and create a roadmap for implementation.
Stage 2: Proof of Concept (PoC): create a proof of concept to assess the complexity of the project. Once the PoC has been approved, you can begin implementing the project.
Stage 3: Follow DevOps: Once the project is ready for implementation, you can start using DevOps phases like version control, continuous integration, continuous testing, continuous deployment, continuous delivery, and continuous monitoring.

Explain Pair Programming.

This type of programming allows two programmers to work on the same project, design, code by following the rules of extreme programming. Among the two programmers, one is the driver and the other is the observer that will monitor the progress of the project continuously and identify the potential failures of the project.

How does Nagios help in the Continuous Monitoring of Systems?

Nagios helps in monitoring the server and how well they are utilized and addresses any failure. It helps in verifying the status of the servers and services. It allows you to inspect the infrastructure’s health. It makes sure that all the applications are working properly and ensure the webs servers are reachable.

Explain Active and Passive checks in Nagios.

Nagios allows the monitoring of hosts and services in two ways.

Actively

It initiates the active checks as a result of the Nagios process
It schedules the active checks regularly

Passively

It initiates the passive checks and performs through external applications/processes
It submits the result of the passive checks to Nagios for processing

Explain Nagios Network Analyzer.

It provides you with an in-depth look at all network traffic sources and security threats.
You will get a central view of our network traffic and bandwidth data.
It allows system admins to gather high-level information on network health.
It ensures that the outages are resolved before they impact the critical business processes.

Explain virtualization in Nagios.

It helps in monitoring metrics on various platforms. It ensures quick detection of failures. You can even monitor the metrics like CPU, memory usages, VM status, and many more.

Conclusion

DevOps has undoubtedly changed the way software development is done and how it is done. It emphasizes team collaboration to improve the system’s productivity and performance. It can be integrated with the latest technology such as Docker, containers, microservices architecture, cloud platforms, and more. Implementing DevOps in your organization will lead to quick success.

We have mentioned some of the interview questions that you can prepare for a better understanding of DevOps and its tools.