scaling

Master the mechanics of scaling distributed systems: when to scale up versus out, why statelessness is the prerequisite for horizontal scale, how L4 and L7 load balancers differ, which balancing algorithm fits which workload, and how to avoid turning your load balancer into the next single point of failure.

The honest case for each. When a monolith is correct, what microservices actually buy you (and what they cost), Conway's law, and how to spot a fake microservices architecture that's actually a distributed monolith.

When one database isn't enough. How sharding splits data across nodes, the trade-offs of different sharding keys, and the operational headaches (hot spots, rebalancing, cross-shard queries) you sign up for.

How load balancers spread traffic across servers, what L4 and L7 actually mean, the routing algorithms in real use, and the failure modes you need to design around.