Virtual networks like any other resource can be provisioned using ARM templates, REST API's, PowerShell, and CLI. It is quite important to plan the network topology at the beginning stage itself to avoid troubles later in the development life cycle. This is because once the network is provisioned and resources start using it, it is difficult to change it without having a downtime. For example, for moving a virtual machine from one network to another will require the virtual machine to shut down.
- Regions: The virtual network is an Azure resource and is provisioned within a region such as West Europe. Applications spanning multiple regions will need separate virtual networks, one per region, ...
