Card 10/ 10
Recap: Load Balancers, Reverse Proxies and API Gateways
Three jobs, two layers, three algorithms and one rule for choosing.
- Three intermediaries, three things behind them: copies, one origin, or many services (Three Servers That Sit in Front of Yours).
- A load balancer makes two decisions per request: which servers are healthy, and which is next (Load Balancers: Spreading Requests Across Servers).
- Round robin takes turns, least connections counts open requests, IP hash keeps a client on one server (Load Balancing Example: Six Requests, Three Algorithms).
- A health check proves only what it touches, so make it touch what a real request needs (Health Checks That Pass While the Application Fails).
- Layer 4 sees addresses and ports; layer 7 reads paths, headers and cookies, at the cost of decrypting TLS (Layer 4 and Layer 7 Load Balancing).
- A reverse proxy terminates TLS, caches and hides one origin (Reverse Proxies).
- An API gateway routes by path and applies authentication and rate limits once (API Gateways).
- Name each part by its job, since one product can play all three (Load Balancer vs Reverse Proxy vs API Gateway).
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