How SLA 99.95% logically achieved when deploying apps with Standard or premium App service plan?

Question

Standard or Premium App Service Plan provides 99.95% SLA. Is that mean, it does maintain Web Apps are replicated or deployed on Azure virtual machines which are located in an Availability set that have Fault domains and update domains.

I'm curious about that, high availability is achieved when running a service on Microsoft Azure virtual machines in an availability set having 2 or more Fault domains and 5 or more update domains which means SLA up-time is guaranteed to 99.95%, where as Microsoft Azure app service (standard and premium) also guarantees SLA up-time to 99.95%.

So My question is whether the app service has a mechanism which uses the same availability set concept of high availability? or it does not use?

Answer 1

Microsoft guarantee that Apps running in a customer subscription will be available 99.95% of the time.

Note: No SLA is provided for Apps under either the Free or Shared tiers.

For more information, refer SLA for App Service.

The compute resources may be on shared or dedicated virtual machines (VMs), depending on the pricing tier that you choose. Your application code runs in a managed VM that is isolated from other customers.

This SLA works based on the fault domain and update domains, understand how fault domains and update domains works in Azure.