Regions, AZs & the Global Network
How AWS's global infrastructure is organized and why it matters for design.
Theory
AWS infrastructure is organized as a hierarchy:
- Region — a geographic area (e.g.
us-east-1), independent and isolated - Availability Zone (AZ) — one or more datacenters in a region with independent power/cooling/networking; regions have 3+ AZs
- Edge locations — hundreds of points of presence for CloudFront (CDN) and DNS
You choose a region based on latency to users, cost, compliance/data residency, and service availability. For high availability, deploy across multiple AZs; for disaster recovery and global latency, use multiple regions.
graph TD R["Region (us-east-1)"] --> A1["AZ a"] R --> A2["AZ b"] R --> A3["AZ c"] G["Global"] --> R G --> E["Edge locations (CDN/DNS)"]
Hands-On Exercise
- List four factors for choosing an AWS region.
- Explain the difference between an Availability Zone and an edge location.
- Describe how multi-AZ deployment improves reliability.
- When would you use multiple regions instead of multiple AZs?
Cheat Sheet▾
| Term | Meaning |
|---|---|
| Region | Isolated geographic area |
| Availability Zone | Independent datacenter(s) in a region |
| Edge location | CDN/DNS point of presence |
| Multi-AZ | High availability within a region |
| Multi-region | DR + global low latency |
| Region choice | Latency, cost, compliance, services |
Common Interview Questions▾
What's the difference between a Region and an Availability Zone?
A Region is an isolated geographic area; an Availability Zone is one or more discrete datacenters within a Region with independent power and networking. A Region contains multiple AZs.
How do you choose which AWS region to use?
Based on latency to your users, data residency/compliance requirements, service availability in that region, and cost (prices vary by region).
Official Documentation
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