High availability within Azure regions

The architecture shown next shows high-availability deployment within a single Azure region. High availability is designed at the individual resource level. In this architecture, as shown in the following diagram, there are multiple VMs at each tier connected through either an application gateway or load balancer, and they are part of an availability set. Each tier is associated with an availability set. These VMs are placed on separate fault and update domains. While the web servers are connected to application gateways, the rest of the tiers, such as application and database tiers, have internal load balancers: