Networking

Introduction Computer networks are the backbone of modern computing. Every time you browse a website, send an email, or stream a video, you rely on a complex stack of protocols, algorithms, and hardware working together. This post is a comprehensive guide to how computer networks work — from the physical transmission of bits to the application-layer protocols you use daily. We will walk through the layered network models (OSI and TCP/IP), dive into each layer’s responsibilities, explore routing and addressing, examine transport-layer reliability, and cover essential application-layer protocols. We will also touch on security, cloud computing, peer-to-peer systems, and distributed architectures like blockchain. ...

Basic Application Architecture Developer Perspective A typical application is composed of: Build & Deploy Layer — CI/CD pipeline Server Layer — handles incoming requests Storage Layer — persists application data (can be external) Logging Storage Server — logs all events Metric Storage Server — logs all metrics Alert Server — alerts when something goes down Stateless vs Stateful Services Stateless: the server holds no session data between requests. Any instance can serve any request. Enables effortless horizontal scaling. Stateful: the server holds session data (e.g. WebSocket connections, in-memory cart). Requires sticky sessions (session affinity at the load balancer) or externalizing state to Redis/a DB. Stateless Stateful Horizontal scaling Trivial — add instances freely Hard — requires sticky sessions or external state Fault tolerance High — any replica serves the request Low — losing a server loses its session data Examples REST APIs, static servers WebSocket servers, game servers, video call nodes User Perspective Users simply make requests to the server and receive responses. ...