Layer decides first, scope second — one tier combo is asymmetric.
A raw TCP/UDP need rules out every Application Load Balancer before scope is even a question.
Global external ALB
Premium Tier only — the default for a global HTTP(S) audience
Regional external ALB
Supports both Premium and Standard Tier
Network Service Tiers: Premium rides Google's private global backbone for consistent latency; Standard uses more public internet transit at lower cost.