The Runtime Theory
System Design

Load Balancers, Explained

Load Balancers, Explained

09:03#load-balancing#architecture#ha

The visual companion to the load balancer article: we build a tiny load balancer in code, watch traffic distribute under a live failing backend, and replay the classic cascade incident in a simulator.

Topics covered:

  • Layer 4 vs layer 7 — what each one sees
  • Health check contracts (liveness vs readiness vs draining)
  • Stickiness and the hot-spot failure
  • The cascade: one dead node, three dead nodes
  • Consistent hashing with bounded churn

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