DevOps Interview Questions and Answers

1) Explain what is DevOps?
It is a newly emerging term in IT field, which is nothing but a practice that emphasizes the
collaboration and communication of both software developers and other information-technology (IT)
professionals. It focuses on delivering software product faster and lowering the failure rate of
releases.

2) Explain how DevOps is helpful to developers?
DevOps can be helpful to developers to fix the bug and implement new features quickly. It also helps
for clearer communication between the team members.

3)List out some popular tools for DevOps?
Some of the popular tools for DevOps are

• Jenkins
• Nagios
• Monit
• ELK (Elasticsearch, Logstash, Kibana)
• io
• Jenkins
• Docker
• Ansible
• Git
• Collectd/Collectl

4) Mention what are the key aspects or principle behind DevOps?
The key aspects or principle behind DevOps is

• Infrastructure as code
• Continuous deployment
• Automation
• Monitoring
• Security

5) What are the core operations of DevOps with application development and with
infrastructure?
The core operations of DevOps with

Application development

• Code building
• Code coverage
• Unit testing
• Packaging
• Deployment

With infrastructure

• Provisioning
• Configuration
• Orchestration
• Deployment

6) Explain how "Infrastructure of code" is processed or executed in AWS?
In AWS,

• The code for infrastructure will be in simple JSON format
• This JSON code will be organized into files called templates
• This templates can be deployed on AWS and then managed as stacks
• Later the CloudFormation service will do the Creating, deleting, updating, etc. operation in the
• stack

7) Mention at what instance have you used the SSH?

I have used SSH to log into a remote machine and work on the command line. Beside this, I have also
used it to tunnel into the system in order to facilitate secure encrypted communications between two
untrusted hosts over an insecure network.

8) Explain how would you handle revision (version) control?

My approach to handle revision control would be to post the code on SourceForge 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.

9) Mention what are the types of Http requests?

The types of Http requests are

• GET
• HEAD
• PUT
• POST
• PATCH
• DELETE
• TRACE
• CONNECT
• OPTIONS

10) Explain what would you check If a Linux-build-server suddenly starts getting slow?

If a Linux-build-server suddenly starts getting slow, you will check for following three things:

Application Level troubleshooting	RAM related issues, Disk I/O read write issues, Disk Space related Issues, etc.
System Level troubleshooting	Check for Application log file OR application server log file, system performance issues, Web Server Log – check HTTP, tomcat log, etc. or check jboss, weblogic logs to see if the application server response/receive time is the issues for slowness, Memory Leak of any application
Dependent Services troubleshooting	Antivirus related issues, Firewall related issues, Network issues, SMTP server response time issues, etc.

11) Explain how you can get the current color of the current screen on the Ubuntu
desktop?

You can open the background image in The Gimp (image editor) and then use the dropper tool to
select the color on the specific point. It gives you the RGB value of the color at that point.

12) Explain what is Memcached?

Memcached is a free and open source, high-performance, distributed memory object caching system.
The primary objective of Memcached is to enhance the response time for data that can otherwise be
recovered or constructed from some other source or database. It is used to avoid the need to operate
SQL data base or another source repetitively to fetch data for concurrent request.

Memcached can be used for

• Social Networking -> Profile Caching
• Content Aggregation -> HTML/ Page Caching
•  Ad targeting -> Cookie/profile tracking
•  Relationship -> Session caching
•  E-commerce -> Session and HTML caching
•  Location-based services -> Data-base query scaling
•  Gaming and entertainment -> Session caching

Memcache helps in

•  Speed up application processes
• It determines what to store and what not to
• Reduce the number of retrieval requests to the database
•  Cuts down the I/O ( Input/Output) access (hard disk)

Drawback of Memcached is

•  It is not a persistent data store
•  Not a database
•  It is not an application specific
•  It cannot cache large object

13) Mention some important features of Memcached?

Important features of Memcached includes

• CAS Tokens: A CAS token is attached to any object retrieved from cache. You can use that token
to save your updated object.
• Callbacks: It simplifies the code
• getDelayed: It reduces the delay time of your script which is waiting for results to come back from
server
• Binary protocol: You can use binary protocol instead of ASCII with the newer client
• Igbinary: Previously, client always used to do serialization of the value with complex data, but with
Memcached you can use igbinary option.

14) Explain what is Dogpile effect? How can you prevent this effect?

Dogpile effect is referred to the event when cache expires, and websites are hit by the multiple
requests made by the client at the same time. This effect can be prevented by using semaphore lock.
In this system when value expires, first process acquires the lock and starts generating new value.

15) Mention what is the difference between Memcache and Memcached?

• Memcache: It is an extension that allows you to work through handy object-oriented (OOP’s) and
procedural interfaces. It is designed to reduce database load in dynamic web applications.

• Memcached: It is an extension that uses libmemcached library to provide API for communicating
with Memcached servers. It is used to increase the dynamic web applications by alleviating database
load. It is the latest API.