Connectivity
When thinking about connectivity, there are two major elements: something to place resources on (i.e., a network) and how to enable communication to that network. In this section, I will explore all the key elements related to connectivity in Azure.
Virtual Networks
Much like a network in a physical location, a virtual network is utilized in Azure as a means to group and provide connectivity between services connected to the network. Virtual networks are broken up into one or more virtual subnets to which the resources are actually connected. A virtual network is bound by both subscription and region and cannot cross those boundaries—i.e., a single virtual network cannot span regions or subscriptions. If you have multiple subscriptions using multiple regions, you must have a virtual network per region, per subscription. (However, you can connect those networks, as I will discuss later.)
The IP space chosen for the virtual network should not overlap any IP space used...
