AWS Global Infrastructure

Three geographic layers

A Region is a geographic area containing multiple Availability Zones, such as ap-southeast-1 (Singapore). An Availability Zone (AZ) is one or more isolated data centers with independent power and networking, connected to the other AZs in the Region through low-latency links. An Edge Location places CloudFront content and Route 53 DNS near users; it is not where you launch EC2.

flowchart TB
  R["Region ap-southeast-1<br/>Singapore"] --> A["AZ 1a<br/>data centers"]
  R --> B["AZ 1b<br/>data centers"]
  R --> C["AZ 1c<br/>data centers"]
  A --> EC2["EC2 + EBS<br/>live in one AZ"]
  E["Edge Location<br/>CloudFront cache"] --> U["Nearby users"]
  %% step R: You choose a Region first: it decides latency, price, available services and where data is stored.
  %% step A: Each Region has at least three AZs, physically separated.
  %% step B: AZs have separate power and networking, so one failing rarely affects the others.
  %% step C: They are close enough for fast synchronous replication between them.
  %% step EC2: An instance, its EBS volumes and its subnet sit in exactly one AZ.
  %% step E: Edge Locations cache content close to users; you do not run servers there.
  %% step U: Users get lower latency for cached static content and DNS answers.

Choosing a Region

Pick a Region by:

1. Compliance and data residency — some data must stay in a country.
2. Latency — closer to users means faster responses.
3. Service availability — new services and instance types do not launch in every Region on day one.
4. Price — the same instance type can cost different amounts in different Regions.

Some newer Regions are opt-in and must be enabled for the account before you can use them.

Resource scope

High availability places workloads in multiple AZs — two instances in two subnets in different AZs behind a load balancer — rather than trying to stretch one subnet or EBS volume across AZs. Disaster recovery for a whole-Region outage goes one step further and copies data or infrastructure to a second Region.

AZ names such as ap-southeast-1a are mapped per account; the letter a in two accounts need not indicate the same physical location. To compare across accounts, use the AZ ID (for example apse1-az1), which is the same everywhere.

Other locations

• Local Zones extend a Region into a metro area for single-digit-millisecond latency.
• Wavelength Zones place compute inside 5G carrier networks.
• Outposts put AWS hardware in your own data center.

You will not use these in the labs, but knowing they exist helps when a question mentions "very low latency to one city" or "AWS services on-premises".

Traps: launching EC2 "in an Edge Location"; assuming an EBS volume can attach to an instance in another AZ; assuming every service exists in every Region.