DevOps Interview Questions and Answer – Part 5

DevOps Interview Questions: Programming

• What is your favorite scripting/programming language(s)? Why ?
• General CS, algorithms Q&A: 5 minutes
  • Data structures – discuss possible implementations and applications:
    • Binary tree
    • Hash map
    • Heap
  • Complexity classes – discuss and give examples:
    • Linear
    • Polynomial
    • NP Complete / NP Hard
  • Sorting algorithms – discuss:
    • What is the fastest sorting algorithm?
    • What is the complexity of quick sort?
  • Distributed systems:
    • What’s Paxos?
    • What’s Raft?
    • What’s consistent hashing?
  • Hands-on coding:
    • Inverse a string in place

DevOps Interview Questions: DevOps

• What DevOps is? Why do we need it?
  • Example of answers:
    • Why do we need it?
      • Increase deployment frequency
      • Lower failure rate of new releases
      • Shortened lead time between fixes
      • Faster mean time to recovery in the event of new release crashing
    • What DevOps is?
      • CALMS
      • C – Culture (promotes collaborative and open culture between Dev and Ops)
      • A – Automation (automate wherever applicable)
      • L- Learning (continuous learning & experimentation)
      • M – Measure (Measure with shared metrics across the Dev and ops for better management)
      • S – Sharing (Shared delivery process across Dev and Ops to build , deploy, maintain and monitor product with mentality of One Team – One Goal)
• What is the purpose of a post-mortem meeting?
• What is meant by Continuous Integration?
• What are the success factors for Continuous Integration?
  • Examples of answers:
    • Maintain a code repository
    • Automate the build
    • Make the build self-testing
    • Everyone commits to the baseline every day
    • Every commit (to baseline) should be built
    • Keep the build fast
    • Test in a clone of the production environment
    • Make it easy to get the latest deliverables
    • Everyone can see the results of the latest build
    • Automate deployment
• How would you implement CI (continuous delivery) – end to end, including source control, branches, tools, etc. ?
• What is Continious Delivery? Continious Deployment?
• What is the difference between Continuous Integration, Continious Delivery and Continious Deployment?
• What’s the difference between git and github ? What about git and SVN ?
• What is git rebase?
• In Git how do you revert a commit that has already been pushed and made public?
• What is puppet/chef/ansible used for? What are the advantages over shell scripts ?
• What do you understand by “Infrastructure as code”? How does it fit into the DevOps methodology? What purpose does it achieve?
• How do you give your developers access to the production logs ?
• Tell me about the worst-run/best-run outage you’ve been a part of. What made it bad/well-run?
• How do you monitor your application ? How do you make sure it is working ? How do you get alerts when it stops working ?
• What would be the availability and performance metrics for a key value store ? What about for MySQL replication ?
• How would you deploy software to 5000 systems?
• What is caching ? Where should a large scale application cache, and what data should be cached ?

DevOps Interview Questions: SysOps

• What is your favorite editor?
• What is RAID? What is RAID0, RAID1, RAID5, RAID10?
• Describe the general file system hierarchy of a Linux system.
• Describe what each of the following command line utilities do:
  • tee
  • awk
  • tr
  • cut
  • curl
  • tail
  • sed
• Command line demo:
  • Search for “my konfu is the best” in all *.py files
  • Replace the occurrence of “my konfu is the best” with “I’m a linux jedi master” in all *.txt files
  • Find all files which have been accessed within the last 30 days
• What is the difference between virtual memory and swap ?
• What is the difference between hardlinks and symlinks?
• What is an inode and what fields are stored in an inode?
• What are zombie processes ?
• Can you have several HTTPS virtual hosts sharing the same IP?
• What is the difference between processes and threads?
• What is the difference between exec and fork?
• How nginx can handle a lot of connections? What does it use inside?
  • Example of answer: Eventloop.
• What is “nohup” used for?
• What is an atomic operation?
• I’ve added my public ssh key into authorized_keys but I’m still getting a password prompt, what can be wrong?
• How do you catch a SIGHUP ? What about SIGSEGV ? What about SIGKILL ?
• What is the Linux Kernel OOM and how does it work ?
• What’s a chroot jail?
• Describe the Linux boot process with as much detail as possible, starting from when the system is powered on and ending when you get a prompt.
• What’s LD_PRELOAD and when is it used?
• You ran a binary and nothing happened. How would you debug this?
• When can a socket receive E_AGAIN ?
• What is a dynamically/statically linked file?
• A careless sysadmin executes the following command: chmod 444 /bin/chmod – what do you do to fix this?
• I’ve lost my root password, what can I do?
• You have accidentally deleted a running script, how could you restore it ?
• What load balancers have you used ?
• AWS:
  • What is the difference between an AMI and an instance ?
  • What’s EBS ? What’s an EBS snapshot ? What is the real cost of having an EBS snapshot ?
  • What’s a VPC ?
  • What’s the difference between a region and an availability zone ?
  • What’s an ELB ?
  • What’s S3 ? What are the features supported on S3 ?

DevOps Interview Questions: DBA

• What’s ACID ? How is it implemented ?
• What is row level locking ? Table level locking ?
• How do you check which jobs are running?
• Imagine you have a filesystem that supports snapshots – how do you take hot backups using volume managers (LVM/EBS)?
• What is the need for master/slave replication in MySQL ? What about master/master replication ? How does replication work in MySQL ?
• How would you handle DB migrations? How would you automate DB migration process?
• What pros/cons could you tell about MySQL/PostgreSQL?

DevOps Interview Questions: Networking

• What is IPv6 ? Why should we care?
• How does ping work ? What about traceroute ?
• I type http://www.yahoo.com in my browser’s URL bar and I press enter. What happens ? (discuss at every OSI layer – Physical, data link, network, transport, session, presentation, application)
  • DNS & anycast, IP, UDP, routing, BGP, TCP, HTTP, transparent proxy
  • What is BGP?
  • What’s a PTR in DNS? Why should we care?
• What if I change from http://www.yahoo.com to https://www.yahoo.com ?
  • Public/private certificates, CAs, proxying, MiTM, etc.
• What happens when I press the send button in my email client ?
• How do we prevent bots crawling ? How would you deal with a syn flood ?
• How many hosts in a /24 network? What about a /22 ?
• What is the difference between DNAT and SNAT ? When do you use either ?
• What is a virtual IP address? What is a cluster?
• What is IPv6 ? Why should we care?

Reference

https://github.com/devops-school/devops-interview-questions

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.