Phase 1 - Foundations

This phase builds the base layer for senior DevOps learning. If Linux, Git, scripting, and networking are weak, everything else will feel harder than it needs to.

Goal

By the end of this phase, you should be able to explain how code moves from a developer workstation to a running service, and how the host and network underneath it behave.

Study Order

1. ../../08_General_Guides_and_Roadmaps/1.-devops-terms.md

2. ../../01_Prerequisites_and_Fundamentals/Linux/README.md

3. ../../01_Prerequisites_and_Fundamentals/Scripting/README.md

4. ../../01_Prerequisites_and_Fundamentals/Networking/README.md

5. ../../02_Version_Control_and_CI_CD/Git_GitHub/Notes_Git_GitHub.pdf

6. ../../07_Interview_Preparation/interview-questions-easy.md

What To Master

DevOps And Systems Thinking

• DevOps as collaboration, automation, feedback, and shared ownership

• Scalability versus availability

• Why observability matters before troubleshooting

• Why toil reduction matters in senior roles

Git And Delivery Hygiene

• clone, branch, commit, merge, rebase, fetch, pull, revert

• pull request flow and protected branches

• the difference between safe rollback and destructive history changes

Linux

• filesystems, permissions, ownership, and sudo

• process inspection, signals, open ports, memory, and disk usage

• systemd, logs, and service management

• package management and CLI fluency

Shell Scripting

• variables, loops, conditions, functions, exit codes

• writing safe Bash scripts

• automating repeated operational tasks

Networking

• IP addressing, CIDR, routing, ports, TCP, UDP

• DNS resolution and troubleshooting

• the difference between timeout, reset, and refused connections

• TLS basics and load balancing

Hands-On Tasks

1. Write a shell script that performs a basic host health check.

2. Use systemctl and journalctl to inspect a running service.

3. Use ss, curl, dig, and ip route on a local or lab machine.

4. Create a small Git repo and practice merge, rebase, revert, and branch cleanup.

5. Explain the full path of a browser request to a backend service in your own words.

Checkpoint Questions

• What is the difference between git revert and git reset?

• How do you identify which process is listening on a port?

• What is the difference between CPU usage and load average?

• What happens during DNS resolution?

• Why does a DevOps engineer need scripting, not just commands?

Exit Criteria

Move to Phase 2 only when you can:

• work comfortably in the terminal without guessing

• explain basic Git collaboration flow

• inspect a Linux host for CPU, memory, disk, and port issues

• explain DNS, TCP, CIDR, and TLS at a practical level

• automate a simple operational task with a script