Complete beginner-friendly guide to computer networks — from IP addresses and DNS to HTTP, TLS, CDNs, and interview prep.

flowchart TB
    Start[Start Here 🚀] --> Fundamentals[01. Fundamentals<br/>IP, DNS, OSI Model]
    Fundamentals --> Transport[02. Transport<br/>TCP, UDP, Handshake]
    Transport --> Web[03. Web Protocols<br/>HTTP, HTTPS, WebSocket]
    Web --> Infra[04. Infrastructure<br/>Load Balancers, CDN, Security]
    Infra --> Interview[05. Interview Prep<br/>Common Q&A]

    style Start fill:#7c3aed,color:#fff
    style Fundamentals fill:#3b82f6,color:#fff
    style Transport fill:#059669,color:#fff
    style Web fill:#06b6d4,color:#fff
    style Infra fill:#f59e0b,color:#fff
    style Interview fill:#ef4444,color:#fff

• What is a Network? — Client/server, internet basics
• OSI & TCP/IP Models — The layers in simple words
• IP Addresses & Ports — IPv4/IPv6, ports, NAT, DHCP
• DNS — Name to IP resolution
• Network Topologies & Devices — Star/mesh/bus, hubs, switches, routers, ARP

• TCP vs UDP — Reliable vs fast, packet structure
• TCP Handshake & Connection — 3-way handshake, teardown
• TCP Flow Control & Congestion — Sliding window, slow start, AIMD

• HTTP & HTTPS — Request/response, methods, TLS
• HTTP Versions — HTTP/1.1 vs HTTP/2 vs HTTP/3
• Status Codes — 1xx–5xx grouped with decision flow
• REST vs WebSocket — Request/response vs persistent two-way
• Cookies, Sessions & CORS — State, cross-origin, CSRF
• HTTP Caching — Cache-Control, ETag, validation

• Load Balancers & Proxies — Forward/reverse proxy, LB algorithms
• CDN & Caching — Edge caching, HTTP cache headers
• Network Security Basics — TLS, firewalls, VPN, DDoS, MITM
• API Gateways & WAF — API gateways, Web Application Firewalls

• Interview Questions — Common networking Q&A