Load Balancing & DNS (the operator’s half)

The two dispatchers: DNS picks which endpoint, the load balancer picks which instance. This lesson is what both jobs look like once real traffic, real failures, and a 3am page show up.

Before you start. You already know how a name resolves - recursive resolver, root, TLD, authoritative server (DNS Resolution), and what’s on the wire (DNS on the wire) - and you’ve met the L4/L7 split - an L4 balancer sees only which address and door a connection is headed for, an L7 one opens the request and reads what is being asked - and built a toy balancer of your own (The chai stall that got famous (load balancing), S2 · Build a Load Balancer). This lesson is what both dispatchers do in production, where they fail, and why the failures look nothing alike.