This repo is agregated guide for preparation to Devops/SRE engineer interview
If you want to thank the author https://www.buymeacoffee.com/mikonoid
Popular Linux Distributions
The most popular linux distrs:
- Ubuntu
- Centos
- Fedora
- Debian
- OpenSuse
- ArchLinux
- Slackware
Comparison: https://www.howtogeek.com/191207/10-of-the-most-popular-linux-distributions-compared/
Linux boot process: from power up to login promt
Explanation:
- BIOS
- MBR
- GRUB
- Kernel
- Init
- Runlevel
Memory types in Linux
Explanation: https://linux-audit.com/understanding-memory-information-on-linux-systems/
What is sticky bit?
Explanation:
What is Virtual memory?
Explanation:
What is zombie process?
Explanation:
File types in Linux
Explanation: https://www.linux.com/tutorials/file-types-linuxunix-explained-detail/
Linux Process Monitor(TOP). Explain all information from top
Explanation:
What is the difference between hardlinks and symlinks?
Explanation:
https://medium.com/@307/hard-links-and-symbolic-links-a-comparison-7f2b56864cdd
What happens if you delete the root user?
Explanation:
- In most cases you will get unbootable system
- https://askubuntu.com/questions/962660/what-happens-if-you-delete-the-root-user
What is a chroot?
Explanation:
https://www.howtogeek.com/441534/how-to-use-the-chroot-command-on-linux/
What is OOM and OOMkiller? How it OOM killer is working
Explanation:
What is kernel panic?
Explanation:
What can you do to restore deleted bash script(script is running but deleted by error)?
Explanation:
See filesystem /proc and find ID proccess in that directory should be script
What happens when a hardlink is removed?
Explanation:
The file will be deleted if you delete only the last hardlink to this file.
Imagine you executed command `chmod -x /bin/chmod`. How to fix this?
Explanation:
Solution1:
cp /bin/cp /tmp/chmod
cp /bin/chmod /tmp/chmod
./tmp/chmod 755 /bin/chmod
Solution2:
perl -e 'chmod(0755, "chmod")`
Solution3:
/lib/ld-linux.so.2 /bin/chmod 755 /bin/chmod
What is Load Average?
Explanation:
http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html
What are cgroups?
Explanation:
What is NAT?
Explanation:
What is ARP?
Explanation:
Address Resolution Protocol. https://en.wikipedia.org/wiki/Address_Resolution_Protocol
How many layers are there under TCP/IP? Compare OSI and TCP/IP
Explanation:
https://techdifferences.com/difference-between-tcp-ip-and-osi-model.html
EXplain TCP 3-way handshake proccess
Explanation:
Explain DNS records: SOA, PTR, A, MX, and CNAME
Explanation:
How to check route table in Linux?
Explanation:
netstat -rn
route -n
ip route list
Server1 can't reach to Server2. Describe possible reasons
Explanation:
- Application layer: Check if servers are correctly configured and services up and running
- Transport layer: Check ports, check ping from server to server
- Network layer: Check firewall and networking setting. Also check routes, dns and ARP tables.
How to check all of open ports on server?
Explanation:
- nmap - if you need check all ports for remote server
- netstat - for localhost
How to check if the last command was run successfully?
Explanation:
echo $? if returns 0 that last command executed successfully
How would you compare two strings in a bash script?
Explanation: Case1:
#!/bin/bash
VAR1="string1"
VAR2="string333"
if [ "$VAR1" = "$VAR2" ]; then
echo "Strings are equal."
else
echo "Strings are not equal."
fi
Case2:
[[ "string1" == "string2" ]] && echo "Equal" || echo "Not equal"
How to print all array elements and their indexes?
Explanation:
#!/bin/bash
array=("A" "B" "C" "X" )
echo ${array[0]}
Print number from 1 to 10 using for loop
Explanation:
#!/bin/bash
for i in {1..10}; do
echo $i
done
How to debug a shell script ?
Explanation:
Option -x
or -nv
Python for sysadmins
Explanation:
How to compile python application?
Explanation:
There are two ways could go about to solve that problem:
- Use a static builder, like freeze, or pyinstaller, or py2exe
- Compile using cython
SQL vs NoSQL. Explain benefits of both
Explanation:
What are tables and field?
Explanation:
What is GIT?
Explanation:
- https://git-scm.com/book/en/v2/Getting-Started-What-is-Git
- https://git-scm.com/book/en/v2/Getting-Started-What-is-Git
What are the benefits of using GIT?
Explanation:
- Documentation
- Markdown
- Fully Distributed
- Simplicity
- Branching model
- open source
What is the difference between `git pull` and `git fetch` ?
Explanation:
What is the difference between `git reset` and `git revert` ?
Explanation:
What is `git rebase` ?
Explanation:
How to reset last commit?
Explanation:
git reset --hard HEAD~1- not a true way cuz you will lost all changesgit revert <commit-id>- good way
for more https://stackoverflow.com/questions/927358/how-do-i-undo-the-most-recent-local-commits-in-git
Describe a dev/test/production workflow using GIT
Explanation:
- https://medium.com/@patrickporto/4-branching-workflows-for-git-30d0aaee7bf
- https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow
What are the advantages of using Docker container?
Explanation:
Docker RUN vs CMD vs ENTRYPOINT
Explanation:
What is the difference between ADD and COPY in Dockerfile?
Explanation: * https://dev.to/lasatadevi/docker-cmd-vs-entrypoint-34e0
What is docker namespaces?
Explanation:
What is docker multistage build? Create one example
Explanation:
Why we need container orchestration?
Explanation:
What is kubernetes?
Explanation: TODO
What are the features of Kubernetes?
Explanation:
What is kubelet?
Explanation: * Kubelet - agent on a kubernetes cluster’s node that takes care of all activity on that node * https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/
What is CNI?
Explanation:
What is headless service?
Explanation:
What are the units of CPU and memory in POD definition?
Explanation:
- CPU is in milicores and memory in bytes
- https://www.noqcks.io/notes/2018/02/03/understanding-kubernetes-resources/
How to deploy stateful application in Kubernetes?
Explanation:
How to expose Kubernetes service?
Explanation: * https://kubernetes.io/docs/tutorials/kubernetes-basics/expose/expose-intro/
Kubernetes deployments strategies: blue-green, canary, rolling
Explanation: * https://traefik.io/glossary/kubernetes-deployment-strategies-blue-green-canary/
Ansible tutorials
Explanation:
Salt tutorials
Explanation:
What is continuous integration?
Explanation:
What is continuous delivery?
Explanation:
What is continuous deployment?
Explanation:
What are the benefits of CI/CD?
Explanation:
Describe a simple CI/CD Pipeline
Explanation:
https://semaphoreci.com/cicd https://www.redhat.com/en/topics/devops/what-is-ci-cd
Jenkins tutorials
Explanation:
- https://www.udemy.com/share/101WuI/
- https://www.youtube.com/playlist?list=PL9ooVrP1hQOGM6eCsjnfAousUSvpqD8dW&ref=hackr.io
- https://jenkins.io/doc/book/
K8S native CI/CD
Explanation:
- Tekton https://github.com/tektoncd
- ArgoCD https://argoproj.github.io/argo-cd/
- JenkinsX https://jenkins-x.io/
Terraform tutorials
Explanation:
- https://www.youtube.com/watch?v=TFLQcgZr0no
- https://www.udemy.com/share/101ZdI/
- https://itnext.io/terraform-tutorial-part-1-intro-and-basic-concepts-7a27ae7722b6
What is terraform modules?
Explanation:
What is ".terraform" directory?
Explanation:
The ".terraform" directory is a local cache where Terraform retains some files required for subsequent operations against this configuration. Its contents are not intended to be included in version control.
What is the usage of Terraform init?
Explanation:
* Terraform init command is used to initialize the working directory containing Terraform configuration files.
* It is used for Plugin Installation.
* It is also used for Child Module Installation.
* It is used for Backend Initialization.
* You can safely run this command multiple times.What do you understand by Terraform Backends? What are the most recommended Backends we should use?
Explanation:
Terraform backends are used to define where and how operations are performed, where state snapshots are stored, etc. Each Terraform configuration can specify a backend.
Reference:
What is terraform lock file?
Explanation:
AWS CloudFormation
Explanation:
- https://www.youtube.com/watch?v=0Sh9OySCyb4
- https://www.simplilearn.com/tutorials/aws-tutorial/aws-cloudformation
What is private cloud?
Explanation:
What is public cloud?
Explanation:
- https://azure.microsoft.com/en-us/overview/what-is-a-public-cloud/
- examples: AWS, GCP, DegitalOcean, Azure
What is cloud service?
Explanation:
AWS tutorials
Explanation:
Google Cloud tutorials
Explanation:
Openstack tutorials
Explanation:
The best resource with Openstack cources is LinuxAcademy https://linuxacademy.com/library/search/openstack/
- Brendan Gregg http://www.brendangregg.com/blog/index.html
- Systems Performance http://www.brendangregg.com/sysperfbook.html
- The Phoenix project https://www.amazon.com/Phoenix-Project-DevOps-Helping-Business/dp/1942788290/
- SRE https://landing.google.com/sre/books/
- Linux System Administration Handbook 5th by Evi Nemeth
- The DevOps Handbook: How to Create World-Class Agility, Reliability, and Security in Technology Organizations