hexplain.hashnode.devHow Cross-Bank ATM Withdrawals Work in India: HDFC, ICICI, and NPCI ExplainedYour account is with HDFC.The ATM belongs to ICICI Bank.Yet the cash comes out instantly, and your HDFC balance updates in real time. So how does this actually work behind the scenes? This article walks through the entire internal flow of a cross-ban...Jan 24·4 min read
hexplain.hashnode.devWebSockets Explained: How Real-Time Communication Works Under the Hood1. Understanding WebSocket Fundamentals Before diving into the internals of WebSockets, it’s important to understand what makes this protocol different from traditional HTTP-based communication. 1.1 What Exactly Is WebSocket? WebSocket is a communica...Jan 23·4 min read
hexplain.hashnode.devLinux Logging 101: A Deep, Practical Guide for DevOps and SREsLogs tell you why. Every real Linux incident eventually leads to logs. SSH failures. Services refusing to start. Instances rebooting without warning. Sudden CPU spikes. Disks filling up overnight. No matter how modern your observability stack is, log...Jan 23·4 min read
hexplain.hashnode.devThe Most Complete, Practical Explanation of Sessions, Cookies, Tokens, and JWTThe HTTP protocol is fundamentally stateless. Every request that reaches a server is treated as an isolated event, with no built-in memory of what happened before. From the server’s point of view, a login request, a page refresh, and an API call all ...Jan 23·5 min read
hexplain.hashnode.devRedis Fundamentals: Caching, Queues, Rate Limiting, and PersistenceWho This Is For This article is written for backend engineers who design, build, deploy, and operate services in real systems, whether that’s for side projects, startups, or production-scale platforms. What You’ll Learn By the end of this guide, you ...Jan 22·5 min read
