Regions, zones and shared responsibility

Cloud providers run data centres around the world and rent capacity to customers on demand.

Regions and availability zones

• A region is a geographic area where a provider operates.
• An availability zone is one or more separate data centres within a region, with independent power and networking.

Spreading resources across more than one zone helps a service survive a single data centre failing. Choosing a region close to your users reduces latency. For many organisations, location also matters for data residency rules, so check your obligations before you choose.

Shared responsibility

The provider secures the underlying infrastructure: facilities, hardware and the core platform. You are responsible for what you build on top: your configuration, your data, who can access it and your application code. Exactly where the line sits depends on the service. A virtual machine leaves you responsible for the operating system, while a managed database takes on more of that work.

Practical takeaway

When something goes wrong in the cloud, first ask whether the problem sits in the provider's layer or in your own configuration. Configuration mistakes are a common source of cloud problems.