As the world of software development evolves, the DevOps methodology has emerged as a game-changer in enhancing collaboration between development and operations teams. Aspiring DevOps professionals often encounter a set of common interview questions to assess their knowledge and expertise. In this blog, we'll provide concise and precise answers to the top 30 DevOps interview questions to help you prepare effectively.
1. How is DevOps different from agile methodology?
Answer: Agile is a software development approach that focuses on incremental and iterative development, while DevOps is a cultural and technical movement that emphasizes collaboration, automation, and continuous delivery. Agile mainly covers the development phase, whereas DevOps extends this collaboration throughout the entire software lifecycle, including operations and support.
2. What are the different phases in DevOps?
Answer: The core phases in DevOps are:
- Continuous Development: Code development and version control.
- Continuous Integration: Frequent merging of code changes into a shared repository.
- Continuous Testing: Automated testing to ensure code quality.
- Continuous Deployment: Automatically deploying code to production-like environments.
- Continuous Monitoring: Monitoring applications and infrastructure for issues.
3. Mention some of the core benefits of DevOps.
Answer: DevOps offers several benefits, including accelerated software delivery, shorter development cycles, increased collaboration, higher reliability, automated processes, faster time-to-market, and improved customer satisfaction.
4. What is the difference between continuous delivery and continuous deployment?
Answer: Continuous Delivery (CD) is the practice of automatically preparing code for deployment but requires human intervention to push it to production. In contrast, Continuous Deployment (CDep) takes the automation one step further by automatically deploying code changes to production without manual intervention.
5. How does continuous monitoring help you maintain the entire architecture of the system?
Answer: Continuous monitoring provides real-time visibility into the system's performance, infrastructure health, and application behavior. It helps in identifying bottlenecks, potential issues, and security threats, allowing for proactive measures and swift problem resolution, thus ensuring a well-maintained architecture.
6. What are the anti-patterns of DevOps?
Answer: DevOps anti-patterns include lack of collaboration between teams, manual and error-prone processes, neglecting security concerns, siloed knowledge, and resistance to automation.
7. What are the key elements of Continuous Testing tools?
Answer: Continuous Testing tools must support automated testing, integration with the development and deployment pipeline, efficient test management, and reporting capabilities.
8. Explain the difference between a centralized and distributed version control system (VCS).
Answer: In a centralized VCS, code is stored in a central server, and developers need to check out and check in code for version control. In contrast, a distributed VCS allows each developer to have their own local copy of the entire repository, promoting better collaboration and flexibility.
9. How is a bare repository different from the standard way of initializing a Git repository?
Answer: A bare repository in Git lacks a working directory and is used as a shared repository for collaboration, while a standard repository includes a working directory and allows developers to make changes.
10. What is the process for reverting a commit that has already been pushed and made public?
Answer: To revert a public commit, create a new commit that undoes the changes introduced by the original commit using the `git revert` command.
11. What is Git stash?
Answer: `Git stash` allows developers to save their local changes temporarily and revert to a clean working directory without committing the changes.
12. How do you find a list of files that have been changed in a particular commit?
Answer: Use the `git show --name-only <commit-id>` command to display the list of files changed in the specified commit.
13. Explain the master-slave architecture of Jenkins.
Answer: In Jenkins, the master node manages the build system and distributes tasks to multiple slave nodes, allowing concurrent builds and efficient resource utilization.
14. Explain the two types of pipelines in Jenkins, along with their syntax.
Answer: Jenkins supports scripted and declarative pipelines. Scripted pipelines use Groovy scripting, while declarative pipelines use a more structured syntax defined within a `pipeline {}` block.
15. How do you create a backup and copy files in Jenkins?
Answer: To create a backup, simply copy the Jenkins home directory. To copy files during a Jenkins build, use build steps or post-build actions like `Copy Artifact` plugin.
16. Explain how you can set up a Jenkins job?
Answer: Setting up a Jenkins job involves defining its name, configuring the source code repository, specifying build steps, and setting post-build actions such as testing and deployment.
17. What is the difference between Assert and Verify commands in Selenium?
Answer: Both `assert` and `verify` commands are used for verification in Selenium. However, if an `assert` fails, the test is terminated, while a `verify` failure allows the test to continue, reporting the failure at the end of the test run.
18. Why are SSL certificates used in Chef?
Answer: SSL certificates in Chef are used to establish secure communication between the Chef server and client nodes, ensuring confidentiality and integrity of data.
19. What is a class in Puppet?
Answer: In Puppet, a class is a re-usable, self-contained block of Puppet code that defines resources and configurations to be applied to target nodes.
20. Explain the architecture of Docker.
Answer: Docker's architecture follows a client-server model. The Docker client communicates with the Docker daemon (server) through a REST API. The daemon manages images, containers, and other resources.
21. What are the advantages of Docker over virtual machines?
Answer: Docker containers share the host OS kernel, resulting in less overhead, faster startup times, and higher density compared to virtual machines.
22. How do you run multiple containers using a single service?
Answer: Define a Docker Compose file with the desired services and configurations, then use `docker-compose up` to run multiple containers simultaneously.
23. Explain the differences between Docker images and Docker containers.
Answer: Docker images are read-only templates used to create Docker containers, which are the running instances of those images.
24. What are the commands used to create a Docker swarm?
Answer: Initialize a swarm using `docker swarm init` on the manager node, and join worker nodes to the swarm using `docker swarm join`.
25. What is the purpose of the expose and publish commands in Docker?
Answer: `Expose` makes ports available within the container, while `publish` maps container ports to host ports, making services accessible externally.
26. What are the port numbers that Nagios uses for monitoring purposes?
Answer: Nagios uses port 5666 for communication between the Nagios server and Nagios client (NRPE).
27. What is an Ansible role?
Answer: An Ansible role is a pre-defined set of tasks, templates, and files that can be reused across multiple playbooks to configure a specific component of a system.
28. What is the Nagios Network Analyzer?
Answer: The Nagios Network Analyzer is a tool that provides in-depth traffic analysis, bandwidth monitoring, and network flow data, helping administrators optimize network performance.
29. What is a hypervisor?
Answer: A hypervisor is software or hardware that enables virtualization by allowing multiple virtual machines to run on a single physical host, each with its own operating system.
30. What are some standard virtualization technologies used in DevOps?
Answer: Common virtualization technologies include VMware, Hyper-V, KVM (Kernel-based Virtual Machine), and Xen.
Happy Devopsing!