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Repository with DevOps interview questions.



  • 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


  • 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 ?


  • 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 ?


  • 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?


  • What is IPv6 ? Why should we care?
  • How does ping work ? What about traceroute ?
  • I type 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 to ?
    • 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?


  • What are some of the most common DevOps personality characteristics ?
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