Book: System Design Pocket Guide: Fundamentals Also by me: LLM Observability Pocket Guide My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub On October 20, 2025, a race condition in DynamoDB's DNS automation produced an empty record for dynamodb.us-east-1.amazonaws.com , and US-EAST-1 went into a 15-hour cascade that took down EC2 launches, Lambda invocations, Fargate tasks, and a long list of services that do not look anything like a database ( AWS DynamoDB outage analysis on InfoQ ). Downdetector logged 6.5M reports across more than 1,000 services. If you read enough public postmortems (Cloudflare, AWS, Google Cloud, Stripe, GitHub), you stop being surprised. The same five failure modes show up over and over. Different companies, different years, different stacks, the same shape of incident. This is the catalog.…