DevOps Interview Questions and Answers for Experienced Pdf
Devops Interview Questions and Answers for Experienced Pdf will be very helpful for the beginners and also for experienced candidates.
1. What is the need for DevOps?
Answer: According to me, this answer should start by explaining the general market trend. Instead of releasing big sets of features, companies are trying to see if small features can be transported to their customers through a series of release trains. This has many advantages like quick feedback from customers, the better quality of software, etc. which in turn leads to high customer satisfaction. To achieve this, companies are required to:
Increase deployment frequency
The lower failure rate of new releases
Shortened lead time between fixes
Faster mean time to recovery in the event of new release crashing
DevOps fulfills all these requirements and helps in achieving seamless software delivery. You can give examples of companies like Etsy, Google, and Amazon which have adopted DevOps to achieve levels of performance that were unthinkable even five years ago. They are doing tens, hundreds or even thousands of code deployments per day while delivering world-class stability, reliability, and security.
2. What are the anti-patterns of DevOps?
Answer: A pattern is a common usage usually followed. If a pattern commonly adopted by others does not work for your organization and you continue to blindly follow it, you are essentially adopting an anti-pattern. There are myths about DevOps. Some of them include.
3. How would you prepare for migration?
Answer: This question evaluates your experience of real projects with all the awkwardness and complexity they bring. Include terms like cut-over, dress rehearsals, roll-back and roll-forward, DNS solutions, feature toggles, branch by abstraction, and automation in your answer. Developing greenfield systems with little or no existing technology in place is always easier than having to deal with legacy components and configuration. As a candidate, if you appreciate that any interesting software system will in effect be under constant migration, you will appear suitable for the role.
4. What is the difference between Scalability and Elasticity?
Answer: Scalability is the ability of a system to increase its hardware resources to handle the increase in demand. It can be done by increasing the hardware specifications or
increasing the processing nodes.
Elasticity is the ability of a system to handle the increase in the workload by adding additional hardware resources when the demand increases(same as scaling) but also
rolling back the scaled resources when the resources are no longer needed. This is particularly helpful in Cloud environments, where a pay per use model is followed.
5. How is Amazon RDS, DynamoDB and Redshift different?
Answer: Amazon RDS is a database management service for relational databases, it manages patching, upgrading, backing up of data, etc. of databases for you without
your intervention. RDS is a Db management service for structured data only.DynamoDB, on the other hand, is a NoSQL database service, NoSQL deals with unstructured data.
Redshift is an entirely different service, it is a data warehouse product and is used in data analysis.
6. If my AWS Direct Connect fails, will I lose my connectivity?
If a backup AWS Direct connects has been configured, in the event of a failure it will switch over to the second one. It is recommended to enable Bidirectional Forwarding
Detection (BFD) when configuring your connections to ensure faster detection and failover. On the other hand, if you have configured a backup IPsec VPN connection
instead, all VPC traffic will failover to the backup VPN connection automatically. Traffic to/from public resources such as Amazon S3 will be routed over the Internet. If
you do not have a backup AWS Direct Connect link or an IPsec VPN link, then Amazon VPC traffic will be dropped in the event of a failure.
7. How can you speed up data transfer in Snowball?
Answer: The data transfer can be increased in the following way:
By performing multiple copy operations at one time i.e. if the workstation is powerful enough, you can initiate multiple cp commands each from different terminals,
on the same Snowball device.
Copying from multiple workstations to the same snowball.
Transferring large files or by creating a batch of small file, this will reduce the encryption overhead.
Eliminating unnecessary hops i.e. make a setup where the source machine(s) and the snowball are the only machines active on the switch being used, this can
hugely improve performance.
8. When should I use Selenium Grid?
Answer: my suggestion would be to give a small definition of Selenium Grid. It can be used to execute the same or different test scripts on multiple platforms and browsers concurrently to achieve distributed test execution. This allows testing under different environments and saving execution time remarkably.
9. What is Ansible module?
Answer: Modules are considered to be the units of work in Ansible. Each module is mostly standalone and can be written in a standard scripting language such as Python, Perl, Ruby, bash, etc.. One of the guiding properties of modules is idempotency, which means that even if an operation is repeated multiple times e.g. upon recovery from an outage, it will always place the system into the same state.
10. Can you explain stand-alone architecture in Puppet?
Puppet can run in a stand-alone architecture, where each managed node has its own complete copy of your configuration info and compiles its own catalog.
In this architecture, managed nodes run the Puppet apply application, usually as a scheduled task or cron job. You can also run it on demand for initial configuration of a server or for smaller configuration tasks.
Like the Puppet master application, Puppet applies needs access to several sources of configuration data, which it uses to compile a catalog for the node it is managing. (Online Training Institute)
11. Explain how Flap Detection works in Nagios?
I will advise you to first explain Flapping first. Flapping occurs when a service or host changes state too frequently, this causes a lot of problem and recovery notifications.
Once you have defined Flapping, explain how Nagios detects Flapping. Whenever Nagios checks the status of a host or service, it will check to see if it has started or stopped flapping. Nagios follows the below-given procedure to do that:
Storing the results of the last 21 checks of the host or service analyzing the historical check results and determine where state changes/transitions occur
Using the state transitions to determine a percent state change value (a measure of change) for the host or service
Comparing the percent state change value against low and high flapping thresholds
A host or service is determined to have started flapping when its percent state change first exceeds a high flapping threshold. A host or service is determined to have stopped flapping when its percent state goes below a low flapping threshold.
12. What are the chef and puppet used for?
Answer: Puppet and Chef are the major configuration management systems on Linux, along with CFEngine, Ansible. More than a configuration management tool, Chef, along with Puppet and Ansible, is one of the industry’s most notable Infrastructure as Code (IAC) tools.
13. What is the difference between an Asset and a Configuration Item?
Answer: According to me, you should first explain Asset. It has a financial value along with a depreciation rate attached to it. IT assets are just a sub-set of it. Anything and everything that has a cost and the organization uses it for its asset value calculation and related benefits in tax calculation fall under Asset Management, and such item is called an asset.
Configuration Item, on the other hand, may or may not have financial values assigned to it. It will not have any depreciation linked to it. Thus, its life would not be dependent on its financial value but will depend on the time until that item becomes obsolete for the organization.
Now you can give an example that can showcase the similarity and differences between both:
Server: It is both an asset as well as a CI.
Building: It is an asset but not a CI.
Document: It is a CI but not an asset
14. What is Git rebase and how can it be used to resolve conflicts in a feature branch before the merge?
Answer: According to me, you should start by saying git rebase is a command which will merge another branch into the branch where you are currently working, and move all of the local commits that are ahead of the rebased branch to the top of the history on that branch.
Now once you have defined Git rebase time for an example to show how it can be used to resolve conflicts in a feature branch before merge, if a feature branch was created from master, and since then the master branch has received new commits, Git rebase can be used to move the feature branch to the tip of master.
The command effectively will replay the changes made in the feature branch at the tip of the master, allowing conflicts to be resolved in the process. When done with care, this will allow the feature branch to be merged into master with relative ease and sometimes as a simple fast-forward operation.
15. What is Continuous Testing?
Answer: I will advise you to follow the below-mentioned explanation:
Continuous Testing is the process of executing automated tests as part of the software delivery pipeline to obtain immediate feedback on the business risks associated with the latest build. In this way, each build is tested continuously, allowing Development teams to get fast feedback so that they can prevent those problems from progressing to the next stage of Software delivery life-cycle. This dramatically speeds up a developer’s workflow as there’s no need to manually rebuild the project and re-run all tests after making changes.
16. What is Automation Testing?
Answer: Automation testing or Test Automation is a process of automating the manual process to test the application/system under test. Automation testing involves the use of separate testing tools which lets you create test scripts which can be executed repeatedly and doesn’t require any manual intervention.
17. Why is Continuous Testing important for DevOps?
Answer: You can answer this question by saying, “Continuous Testing allows any change made in the code to be tested immediately. This avoids the problems created by having “big-bang” testing left to the end of the cycle such as release delays and quality issues. In this way, Continuous Testing facilitates more frequent and good quality releases.”
18. What are the goals of Configuration management processes?
Answer: The purpose of Configuration Management (CM) is to ensure the integrity of a product or system throughout its life-cycle by making the development or deployment process controllable and repeatable, therefore creating a higher quality product or system. The CM process allows orderly management of system information and system changes for purposes such as to:
Reliability or maintainability,
Reduce risk and
Liability, or correct defects.
19. How can I set deployment order for applications?
Answer: WebLogic Server 8.1 allows you to select the load order for applications. See the Application MBean Load Order attribute in Application. WebLogic Server deploys server-level resources (first JDBC and then JMS) before deploying applications. Applications are deployed in this order: connectors, then EJBs, then Web Applications. If the application is an EAR, the individual components are loaded in the order in which they are declared in the application.xml deployment descriptor.
20. Explain how would you handle revision (version) control?
Answer: My approach to handling revision control would be to post the code on Source Forge or GitHub so everyone can view it. Also, I will post the checklist from the last revision to make sure that any unsolved issues are resolved.
21. What Is Devops With Cloud Computing?
Answer: Inseparable development and operations practices are universally relevant. Cloud computing, agile development, and DevOps are interlocking parts of a strategy for transforming IT into a business adaptability enabler. If the cloud is an instrument, then DevOps is the musician that plays it.
22. Why do we use the chef-Jenkins plugin in chef?
Answer: Chef-Jenkins adds the ability to use Jenkins to drive continuous deployment and synchronization of environments from a git repository.
23. What is a puppet module command?
Answer: The puppet module command provides an interface for managing modules from the Puppet Forge. Its interface is similar to several common package managers (such as gem, apt-get, or yum). You can use the puppet module command to search for, install, and manage modules.
24. What’s Special About Puppet’s Model-driven Design?
Traditionally, managing the configurations of a large group of computers has meant a series of imperative steps; in its rawest state, SSH and a for a loop. This general approach grew more sophisticated over time, but it retained the more profound limitations at its root.
Puppet takes a different approach, which is to model everything: the current state of the node, the desired configuration state, the actions taken during configuration enforcement as data: each node receives a catalog of resources and relationships, compares it to the current system state, and makes changes as needed to bring the system into compliance.
The benefits go far beyond just healing the headaches of configuration drift and unknown system state: modeling systems as data let Puppet simulate configuration changes, track the history of a system over its lifecycle, and prove that refactored manifest code still produces the same system state. It also drastically lowers the barrier to entry for hacking and extending Puppet: instead of analyzing code and reverse-engineering the effects of each step, a user can just parse data, and sysadmins have been able to add significant value to their Puppet deployments with an afternoon’s worth of Perl scripting.
25. Which are the top DevOps tools? Which tools have you worked on?
Answer: The most popular DevOps tools are mentioned below:
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
You can also mention any other tool if you want, but make sure you include the above tools in your answer.
The second part of the answer has two possibilities:
If you have experience with all the above tools then you can say that I have worked on all these tools for developing good quality software and deploying that software easily, frequently, and reliably.
If you have experience only with some of the above tools then mention those tools and say that I have specialization in these tools and have an overview of the rest of the tools.
26. What is the use of etckeeper-commit-post and etckeeper-commit-pre on Puppet Agent?
Answer: Answer to this question is pretty direct just tell the uses of the above commands:
etckeeper-commit-post: In this configuration file you can define command and scripts which executes after pushing configuration on Agent.
etckeeper-commit-pre: In this configuration file you can define command and scripts which executes before pushing configuration on Agent.
I hope you have enjoyed the above set of Puppet interview questions, the next set of questions will be more challenging, so be prepared.
27. Explain how DevOps is helpful to developers?
DevOps brings faster and more frequent release cycles which allow developers to identify and resolve issues immediately as well as implementing new features quickly.
Since DevOps is what makes people do better work by making them wear different hats, Developers who collaborate with Operations will create software that is easier to operate, more reliable, and ultimately better for the business.
28. What DevOps tools have you worked with?
Answer: Software configuration management and build/release (version control) tools, including Apache Subversion, Mercurial, Fossil and others, help document change requests. Developers can more easily follow the company’s best practices and policies while software changes.
Continuous integration (CI) tools such as Rational Build Forge, Jenkins and Semaphore merge all developer copies of the working code into a central version. These tools are important for larger groups where teams of developers work on the same codebase simultaneously. QA experts use code analyzers to test software for bugs, security, and performance. If you’ve used HP’s Fortify Static Code Analyzer, talk about how it identified security vulnerabilities in coding languages. Also speak about tools like GrammaTech’s CodeSonar that you used to identify memory leaks, buffer underruns and other defects for C/C++ and Java code. It is essential that you have an adequate command of the principal languages like Ruby, C#, .NET, Perl, Python, Java, PHP, Windows PowerShell, and are comfortable with the associated OS environments Windows, Linux, and Unix.
29. Why has DevOps gained prominence over the last few years?
Before talking about the growing popularity of DevOps, discuss the current industry scenario. Begin with some examples of how big players such as Netflix and Facebook are investing in DevOps to automate and accelerate application deployment and how this has helped them grow their business. Using Facebook as an example, you would point to Facebook’s continuous deployment and code ownership models and how these have helped it scale up but ensure the quality of experience at the same time. Hundreds of lines of code are implemented without affecting quality, stability, and security.
Your next use case should be Netflix. This streaming and on-demand video company follow similar practices with fully automated processes and systems. Mention the user base of these two organizations: Facebook has 2 billion users while Netflix streams online content to more than 100 millions users worldwide. These are great examples of how DevOps can help organizations to ensure higher success rates for releases, reduce the lead time between bug fixes, streamline and continuous delivery through automation, and an overall reduction in manpower costs.
30. What is the role of AWS in DevOps?
Answer: When asked this question in an interview, get straight to the point by explaining that AWS is a cloud-based service provided by Amazon that ensures scalability through unlimited computing power and storage. AWS empowers IT enterprises to develop and deliver sophisticated products and deploy applications on the cloud. Some of its key services include Amazon Cloud Front, Amazon SimpleDB, Amazon Relational Database Service, and Amazon Elastic Computer Cloud. Discuss the various cloud platforms and emphasize any big data projects that you have handled in the past using cloud infrastructure
31. Explain how you can minimize the Memcached server outages?
When one instance fails, several of them goes down, this will put a larger load on the database server when lost data is reloaded as the client make a request. To avoid this, if your code has been written to minimize cache stampedes then it will leave a minimal impact
Another way is to bring up an instance of Memcached on a new machine using the lost machines IP address
Code is another option to minimize server outages as it gives you the liberty to change the Memcached server list with minimal work
Setting timeout value is another option that some Memcached clients implement for Memcached server outage. When your Memcached server goes down, the client will keep trying to send a request till the time-out limit is reached.
32. Is continuous delivery related to the dev-ops movement? How so?
Answer: Absolutely. In any organization where there is a separate operations department, and especially where there is an independent QA or testing function, we see that much of the pain in getting software delivered is caused by poor communication between these groups, exacerbated by an underlying cultural divide. Apps are measured according to throughput, and ops are measured according to stability. Testing gets it in the neck from both sides, and like release management, is often a political pawn in the fight between apps and ops. The point of dev-ops is that developers need to learn how to create high-quality, production-ready software, and ops need to learn that Agile techniques are actually powerful tools to enable effective, low-risk change management. Ultimately, we’re all trying to achieve the same thing – creating business value through software – but we need to get better at working together and focusing on this goal rather than trying to optimize our own domains. Unfortunately, many organizations aren’t set up in a way that rewards that kind of thinking. According to Forrester.
33. What Is Aws Code Build In Aws Devops?
Answer: AWS Code Build is a fully managed build service that compiles source code, runs tests, and produces software packages that are ready to deploy. With Code Build, you don’t need to provision, manage, and scale your own build servers. Code Build scales continuously and processes multiple builds concurrently, so your builds are not left waiting in a queue.
34. What is the way to secure data for carrying in the cloud?
Answer: One thing must be ensured that no one should seize the information in the cloud while data is moving from point one to another and also there should not be any leakage with the security key from several storerooms in the cloud. Segregation of information from additional companies’ information and then encrypting it by means of approved methods is one of the options.
35. Can I connect my corporate data center to the Amazon Cloud?
Answer: Yes, you can do this by establishing a VPN(Virtual Private Network) connection between your company’s network and your VPC (Virtual Private Cloud), this will allow
you to interact with your EC2 instances as if they were within your existing network.
36. Can S3 be used with EC2 instances, if yes, how?
Yes, it can be used for instances with root devices backed by local instance storage. By using Amazon S3, developers have access to the same highly scalable, reliable,
fast, inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. In order to execute systems in the Amazon EC2 environment,
developers use the tools provided to load their Amazon Machine Images (AMIs) into Amazon S3 and to move them between Amazon S3 and Amazon EC2.
37. The top 10 skills the person should be having for the DevOp’s position?
Excellent in System Admin
Good Technical Skills
Good Developing skills
Chef in Automation Tool Experience
Real-time Cloud operations
Who cares about someone
38. Why do you need a Continuous Integration of Dev & Testing?
Answer: Continuous Integration of Dev and Testing improves the quality of software, and reduces the time taken to deliver it, by replacing the traditional practice of testing after completing all development. It allows the Dev team to easily detect and locate problems early because developers need to integrate code into a shared repository several times a day (more frequently). Each check-in is then automatically tested.
39. Explain how can create a backup and copy files in Jenkins?
Answer: all you need to do is to periodically back up your JENKINS_HOME directory. This contains all of your build jobs configurations, your slave node configurations, and your build history. To create a back-up of your Jenkins setup, just copy this directory. You can also copy a job directory to clone or replicate a job or rename the directory.
40. Which Testing tool are you comfortable with and what are the benefits of that tool?
Answer: Here mention the testing tool that you have worked with and accordingly frame your answer. I have mentioned an example below:
- I have worked on Selenium to ensure high quality and more frequent releases.
- Some advantages of Selenium are:
- It is free and open-source
- It has a large user base and helping communities
- It has cross Browser compatibility (Firefox, Chrome, Internet Explorer, Safari, etc.)
- It has great platform compatibility (Windows, Mac OS, Linux, etc.)
- It supports multiple programming languages (Java, C#, Ruby, Python, Pearl, etc.)
- It has fresh and regular repository developments
- It supports distributed testing
41. Which open source or community tools do you use to make Puppet more powerful?
Answer: Explain about some tools that you have used along with Puppet to do a specific task. You can refer the below example:
Changes and requests are ticketed through Jira and we manage requests through an internal process. Then, we use Git and Puppet’s Code Manager app to manage Puppet code in accordance with best practices. Additionally, we run all of our Puppet changes through our continuous integration pipeline in Jenkins using the beaker testing framework.
42. What is Module and How it is different from Manifest?
Answer: Whatever the manifests we defined in modules, can call or include into other manifests. Which makes easier management of Manifests. It helps you to push specific manifests on a specific Node or Agent.
43. Describe the most significant gain you made from automating a process through Puppet?
Answer: “I automated the configuration and deployment of Linux and Windows machines using Puppet. In addition to shortening the processing time from one week to 10 minutes, I used the roles and profiles paradigm and documented the purpose of each module in README to ensure that others could update the module using Git. The modules I wrote are still being used, but they’ve been improved by my teammates and members of the community.”
44. What if I haven’t signed a CLA?
Answer: If you haven’t signed a CLA, then we can’t yet accept your code contribution into Puppet or Factor. Signing a CLA is very easy: simply log into your GitHub account and go to our CLA page to sign the agreement.
We’ve worked hard to try to find to everyone who has contributed code to Puppet, but if you have questions or concerns about a previous contribution you’ve made to Puppet and you don’t believe you’ve signed a CLA, please sign a CLA or contact us for further information.
45. What are the types of environments?
Answer: The main uses for environments fall into three categories: permanent test environments, temporary test environments, and divided infrastructure.
46. What are the containers?
Answer: My suggestion is to explain the need for containerization first, containers are used to provide a consistent computing environment from a developer’s laptop to a test environment, from a staging environment into production.
Now give a definition of containers, a container consists of an entire runtime environment: an application, plus all its dependencies, libraries and other binaries, and configuration files needed to run it, bundled into one package. Containerizing the application platform and its dependencies remove the differences in OS distributions and underlying infrastructure.
47. How to automate Testing in DevOps lifecycle?
Answer: I have mentioned a generic flow below which you can refer to:
In DevOps, developers are required to commit all the changes made in the source code to a shared repository. Continuous Integration tools like Jenkins will pull the code from this shared repository every time a change is made in the code and deploy it for Continuous Testing that is done by tools like Selenium as shown in the below diagram.
In this way, any change in the code is continuously tested, unlike the traditional approach.