Week 4 covered the upper layers of the AWS storage stack. S3's internal consistency model and large-scale operational patterns (Day 16), the eight storage classes and the economics of lifecycle policies (Day 17), the five access-control layers and encryption key management (Day 18), and CloudFront's three-layer cache structure and hybrid storage patterns (Day 19). These four topics are the core of the "data storage" domain that appears most often on the exam.
Today's goal is to organize this not as rote memorization but as a decision system