Query on mandated vnet peering when using internal IPs in backend pools

Question

Hi,

In the component basics section of documentation [1], it notes "If you use internal IPs as backend pool members, you must use virtual network peering or a VPN gateway. Virtual network peering is supported and beneficial for load-balancing traffic in other virtual networks.
In the Terraform Quickstart example [2], however, in the main.tf example, the private IP in the backend subnet is in a subnet that is in the same Virtual Network as the AG front end subnet, and no peering is used.

So, is peering mandated, or simply recommended/best practise?

Many thanks,

[1] https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-components
[2] https://learn.microsoft.com/en-us/azure/developer/terraform/deploy-application-gateway-v2?toc=%2Fazure%2Fapplication-gateway%2Ftoc.json&bc=%2Fazure%2Fapplication-gateway%2Fbreadcrumb%2Ftoc.json

Answer 1

From my understanding, the "Internal IPs" mentioned in the documentation refers to the following:

(...)As a result, the members of the backend pools can be across clusters, across datacenters, or outside Azure, as long as there's IP connectivity.(...)

If the backend pool is in the same VNet, no need.