Load Balancer: The Traffic Cop of High Scale Systems (L4 vs L7)

11. Summary: What I Learned from Load Balancers

The core insights I gained from load balancers:

1. Scaling out is easy, distributing traffic is hard. Without load balancers, scale-out is meaningless.
2. L4 vs L7 is a "performance vs features" tradeoff. L7 isn't always better.
3. Avoid Sticky Sessions, embrace Stateless Architecture. Sessions belong in external stores like Redis.
4. Without Health Checks and Connection Draining, zero-downtime deployment is impossible.
5. Load balancers can die too. Eliminate SPOF by making load balancers redundant.

One-line summary: "Load balancers aren't just traffic distribution tools. They're core components of high-availability systems."