AWS Interview DropAdvanced TierScenario+50 XP on read
You have a dozen VPCs that all need to reach each other and a shared-services VPC. Would you use VPC Peering or Transit Gateway, and why?
Core Summary
Peering connects two VPCs directly and doesn't scale past a handful of them, since connections grow quadratically and traffic can't transit through a peered VPC to reach a third. Transit Gateway is a central routing hub that turns the same problem into one connection per VPC, and it's the right call anywhere past three or four VPCs.
Hints
Hint 1: Peering connections don't transit; A-to-B and B-to-C doesn't give you A-to-C
Hint 2: Count the connections: peering is quadratic, Transit Gateway is linear
Hint 3: Transit Gateway costs more per hour and per GB, and that's the actual trade-off