Health Check (LB)
Periodic probes a load balancer sends to backend servers to verify they're alive. Unhealthy servers get pulled from the rotation until they recover.
What is Health Check (LB)?
Periodic probes a load balancer sends to backend servers to verify they're alive. Unhealthy servers get pulled from the rotation until they recover.
Health Check (LB) is a foundational concept that sits in the Load Balancing & Proxies area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "Health Check (Load Balancing)" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
Learn Health Check (LB) in depth
Full interactive lesson with diagrams, code examples, real-world references, and a quiz.
Open the Health Check (Load Balancing) lessonSee also
Related glossary terms you might want to look up next.
Load Balancer
Distributes incoming traffic across multiple servers so no single server gets overwhelmed. Like a traffic cop directing cars to different lanes.
Fault Tolerance
A system's ability to keep operating correctly even when some of its components fail. Achieved through redundancy, replication, and graceful degradation.
Health Check
An endpoint or mechanism that reports whether a service is running and healthy. Load balancers use health checks to route traffic away from unhealthy instances.