08. Load Balancing and Horizontal Scaling

Episode 8 of 34 | System Design: From Fundamentals to Interview Mastery An original flash-sale example follows traffic through transport and application balancing, algorithm choice, readiness, connection draining, state externalization, bounded retries, and capacity planning. The lesson distinguishes balanced request counts from balanced work and keeps inventory correctness outside the load balancer. Original script, worked examples, diagrams and animation. Adapted educational presentation; no endorsement implied. Voice generated locally with the speaker's authorization. Chapters 0:00 Welcome and what we will cover 0:11 Three servers can still produce one overloaded service 1:24 Layer four and layer seven see different information 2:59 Pick a routing algorithm from the workload 4:23 Readiness, liveness and passive failure signals differ 5:49 Stateless instances make routing changes safer 7:09 Drain connections without duplicating a checkout 8:32 Plan the load balancer and fleet for failure 10:00 Present the complete balancing argument 11:31 Recap, practice and thank you