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R&D

AWS Global Infrastructure — Regions, AZs, Edge

The three layers

Section titled “The three layers”
Regions (31+) → AZs (99+, 3-6/region) → Edge locations (400+)
Region AZ Edge
Mental model Legal boundary Parallel running buildings Cache kiosks
Purpose Compliance/data residency, where services run, DR unit High availability (failover + active-active) Latency (content near users)
Runs your app? Yes Yes NO — cache + DNS + Shield only
Example us-east-1, ap-southeast-3 (Jakarta) AZ-a, AZ-b, AZ-c 400+ points of presence

Corrected mental models

Section titled “Corrected mental models”
Region = OBEY LOCAL LAW — data residency, compliance, DR to 2nd region
AZ     = BACKUP (failover) + LOAD-BALANCED parallel instances (active-active HA)
Edge   = LATENCY — cache content near users (CloudFront), DNS (Route 53), DDoS (Shield)
  • AZs: independent power/cooling/network, linked by low-latency fiber
  • Active-passive (standby) OR active-active (ALB spreads, one absorbs if other dies)
  • AZs used by: EC2, RDS Multi-AZ, EBS, DynamoDB (3 AZs default)
  • Regions NOT for “reaching customers” — that’s edges. Regions for compliance/DR

Exam scenarios

Section titled “Exam scenarios”
  • “high availability across buildings” → AZs (multi-AZ)
  • “data must stay in Indonesia” → ap-southeast-3 region (Jakarta)
  • “reduce latency for global users” → CloudFront edge locations
  • “disaster recovery, region on fire” → second region
Section titled “Related”
  • [[aws/index]]
  • [[aws/cloudfront/index]]