You now understand how systems communicate.
DNS translates domain names to IP addresses. Caching and TTL matter for performance.
HTTP is request-response. HTTPS encrypts everything.
REST is the default. GraphQL for complex queries. gRPC for fast service-to-service calls.
WebSockets enable real-time bidirectional communication.
API Gateway provides a single entry point to multiple services.
Next, you'll learn about NoSQL databases and when to choose them over SQL.