Setting up your application across multiple fault domains is a way to configure high availability for an application in an OCI region with a single availability domain. A fault domain is a logical grouping of hardware and infrastructure within an availability domain that is designed to be isolated from failures in other fault domains. Fault domains let you distribute your instances so that they are not on the same physical hardware within a single availability domain. This reduces the impact of hardware failures, power outages, or network issues on your application availability and performance. Each availability domain has three fault domains, regardless of the number of availability domains in a region1