Case studies

Real infrastructure, studied on its own terms. Company cases describe only publicly documented architecture and cite every source; pattern studies teach the designs the exam expects you to reach for.

Airbnb: growing up on AWSA Rails monolith on 200 EC2 instances became 250 services, and every step of the surgery happened while the marketplace stayed open.2.1 2.2Duolingo: serving streaks to 100+ million learners on DynamoDBOne row per learner per course, tens of billions of items, and a cache TTL change that erased 2.1 billion API calls a day.3.3 4.3Event-driven decoupled processing with SQS, SNS, and LambdaOne publish, many independent consumers: how a queue and a topic let each part of a system fail, retry, and scale on its own.2.1 3.2Global static site and media delivery with S3 and CloudFrontStore the bytes once in a private bucket, serve them everywhere from the edge, and never open the bucket to the internet.3.4 3.1Prime Day: AWS stress-testing itselfEvery July Amazon aims the largest retail traffic spike on earth at its own cloud, then publishes the meter readings for anyone who wants to study them.2.1 3.3Serverless data lake and analytics with S3, Glue, and AthenaStore everything once in S3, catalog it with Glue, and query it in place with Athena, so you pay for compute only when a query actually runs.3.5 3.1The default three-tier web app: ALB, Auto Scaling, and RDS Multi-AZThe single most-tested shape on the SAA exam: how a public load balancer, a self-healing compute fleet, and a database with a hot standby combine to survive an Availability Zone failure.2.1 2.2The three-tier web app, done properlyALB, Auto Scaling across AZs, RDS Multi-AZ, and CloudFront on top, because half the associate exam is this one diagram and the places it can fall over.2.2 3.2