What is the scale? (e.g., 100 million Daily Active Users.) 2. Back-of-the-Envelope Estimates

How much network traffic will the system generate?

The book walks through "recurring components" that serve as the foundation for almost any design question:

Choose Cassandra for massive write-heavy logs, MongoDB for unstructured documents, or DynamoDB for highly scalable key-value lookups. Load Balancing and API Gateways