Public, private and hybrid cloud

A cloud model describes where the cloud resources live and who can use them. AZ-900 expects you to know three main models and to pick the right one for a scenario.

Public cloud

Resources are owned and operated by a provider (such as Microsoft) and shared by many customers over the internet. Each customer's data is isolated, but the hardware is not dedicated to one organisation.

• No capital expenditure; pay for what you use
• Huge scale, available in minutes
• Use it when you want speed, flexibility and no hardware to manage

Private cloud

Cloud computing resources used by one organisation only. It can be hosted in the organisation's own data centre or by a third party, but it is not shared.

• Full control over hardware, security and configuration
• The organisation buys and maintains the hardware (capital expenditure)
• Use it when strict regulations or legacy requirements demand complete control

Hybrid cloud

A combination of public and private clouds, connected so that data and applications can move between them.

• Keep sensitive or regulated workloads on-premises; use the public cloud for everything else
• Use the public cloud for extra capacity at busy times ("cloud bursting")
• Use it when some systems must stay on-premises but you still want public cloud flexibility

Multi-cloud

Using more than one public cloud provider, for example Azure and another provider. Organisations do this to use features from each provider or during a migration. It adds management complexity.

Compare them