A health check tests if an instance is ready to serve traffic. Load balancers use it to remove unhealthy instances from rotation, improving availability and reducing user-facing errors.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Explain the "why", not just the "what" (intuition + consequences).
Trade-offs: what you gain/lose (time, memory, complexity, risk).
Edge cases: empty inputs, large inputs, invalid inputs, concurrency.
Examples
A tiny example (an explanation template):
// Example: discuss trade-offs for "health-checks:-what-are-they-and-why-do-load-bal"
function explain() {
// Start from the core idea:
// A health check tests if an instance is ready to serve traffic. Load balancers use it to re
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).