In one of the interviews I was asked the below question. Does the IAAS communicate with PAAS services over the vnet ?
How IAAS communicate with PAAS services
Does the IAAS communicate with PAAS services over the vnet ?
Yes, Within the Same Virtual Networks, across the virtual networks via peering or via VPN/Express Route -- Azure PaaS and IaaS services can communicate with each other.
How IAAS communicate with PAAS services
As long as the services are reachable via an IP/Port, there are numerous methods to communicate /connect like VNet, Express Route, Peering service, Azure DNS, Bastion, etc.
Refer to the Azure Networking Services for more information.