Design a load balancer that distributes traffic across a fleet of backend servers.

Looks simple until the follow-ups: which layer do you balance at, how do you keep traffic off a dead server, and how does the load balancer itself avoid being a single point of failure? Interviewers want the algorithm, the health-check loop, and the high-availability story.

Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.