Picking the wrong tier can mean the requirement can't be met at all.

Global/regional, external/internal, Layer 4/Layer 7 — a real capability decision, not a cost one.

Layer 4 (Network LB)No HTTP visibility — can't route by path or header

Layer 7 (Application LB)Full HTTP semantics — path, header, cookie routing

Cloud CDNCaches at the edge — cached responses never reach origin

Cloud DNS supports public zones (external) and private zones (resolvable only inside a VPC) — genuinely useful for internal service discovery that shouldn't be publicly resolvable.