AWS Global Infrastructure¶

1. The Hierarchy¶

AWS Cloud
   └── Regions  (geographic groupings)
         └── Availability Zones / AZs  (isolated fault boundaries)
               └── Data Centers  (physical buildings with hardware)

Resources live in Data Centers — not directly in Regions or AZs. Region and AZ are logical groupings on top of physical infrastructure.

2. Current Numbers (Official — March 2026)¶

Rule: These numbers keep increasing. Always verify at aws.amazon.com/about-aws/global-infrastructure.

3. Data Center¶

Definition: A physical facility containing servers, storage, and networking equipment.

• Real physical location — actual hardware lives here
• Highly secured (biometric, 24/7 surveillance, redundant power)
• AWS does NOT expose how many DCs exist per AZ
• Focus on logical design, not counting buildings

4. Availability Zone (AZ)¶

Definition: One or more Data Centers grouped together, treated as a single logical unit.

AZ = Failure Boundary — the core reason multi-AZ architecture exists.

5. Region¶

Definition: A geographic area containing a cluster of multiple, isolated AZs.

Example — Mumbai Region:

Region:  ap-south-1
AZs:     ap-south-1a
         ap-south-1b
         ap-south-1c

6. Naming Convention ⭐¶

Region name breakdown:

ap  -  south  -  1
 ↓       ↓       ↓
Asia   location  region
Pacific          number

Rule: Ends with a number = Region. Ends with a letter = AZ.

Common region prefixes:

7. AZ Identity Per Account (Important Correction) ⭐¶

AWS does not expose all AZs to every account — and AZ names are not consistent across accounts.

Your account:       ap-south-1a  →  maps to  Physical Zone ID: aps1-az1
Another account:    ap-south-1a  →  maps to  Physical Zone ID: aps1-az2

Same AZ name, different physical location. AWS does this for capacity management and load distribution. To compare actual physical AZs across accounts → use AZ ID (e.g. aps1-az1), not AZ name.

Enable additional AZs: Some AZs are not enabled by default in new accounts. You opt in via the console under Account Settings.

8. Edge Locations ⭐¶

Definition: Points of Presence (PoPs) deployed in cities worldwide — closer to end users than Regions.

Used by: Amazon CloudFront (CDN), Route 53, AWS Shield, Lambda@Edge

Request flow:

User
 ↓
Edge Location  ← cache hit? serve directly ✅
 ↓ (cache miss)
Regional Edge Cache  ← cache hit? serve from here ✅
 ↓ (cache miss)
AWS Region  ← fetch from origin (your EC2/S3/etc.)

Edge Locations are NOT Regions or AZs — they do not run compute workloads. They exist purely for low latency content delivery and DNS resolution.

9. Local Zones & Wavelength Zones (Bonus — Interview Aware)¶

These sit outside the main Region but are extensions of it. Local Zone example: us-west-2-lax-1a (Los Angeles Local Zone of Oregon Region).

10. Regional vs Global Services ⭐¶

Global Services (not tied to any Region)¶

Regional Services (tied to a specific Region)¶

AZ-Specific Resources (bound to a single AZ)¶

Exam rule: If you can't select a Region in the console for a service → it's Global.

11. AWS Console — Control Plane¶

Definition: Web interface to manage AWS resources. Console sends commands via API → Region → AZ → Data Center → Resource. Console stores no data — it is purely a control plane.

Key Console Components¶

Region Selector is critical — always verify selected Region before creating a resource. Default Region for new accounts: us-east-1 (N. Virginia).

Resource Creation Flow¶

You click "Launch EC2" in console
           ↓
Console → AWS API
           ↓
Selected Region (e.g. ap-south-1)
           ↓
Selected AZ (e.g. ap-south-1a)
           ↓
Physical Data Center
           ↓
Resource Created ✅

User Access Flow¶

User Request
     ↓
Edge Location (CloudFront PoP — nearest to user)
     ↓  (cache miss)
AWS Region
     ↓
AZ → Data Center → Your Resource
     ↓
Response back via same path ✅

12. Why This Architecture Exists¶

13. Common Mistakes ✅¶

14. Interview Questions Checklist ✅¶

• What is the AWS Global Infrastructure hierarchy?
• How many Regions and AZs does AWS have? (current numbers)
• What is a Region? How do you choose one?
• What is an Availability Zone? Why does it exist?
• What is the difference between a Region and an AZ?
• Decode this: ap-southeast-1b — what is it?
• What is an Edge Location? How is it different from a Region?
• What are Regional Edge Caches?
• What are Local Zones? What are Wavelength Zones?
• Name 5 Global services and 5 Regional services
• Why is IAM global but EC2 regional?
• What does the Region Selector in AWS Console do?
• Why do AZ names differ between accounts?
• What is an AZ ID and why is it more reliable than AZ name?
• What is us-east-1 and why is it the default?
• What happens when you create an EC2 instance — which components are involved?