During this lecture, we'll explore the fundamentals of Microsoft Azure Virtual Network in Microsoft Azure Resource Manager (ARM). Virtual Networks are created as top-level entities within an ARM Resource Group. Each Virtual Network has one or more address spaces (prefixes / CIDR blocks) associated with it, and one or more subnets. A subnet can fill the entire space of an address prefix, or it can be defined as a subset of the available address space. In order to utilize Azure VPN Gateway, a Virtual Network must have a subnet named "GatewaySubnet" that is a /29, or larger.

Once a Virtual Network and its subnets have been created, resources can be provisioned into them, by associating each resource to one of the Virtual Network's subnets. For example, to connect a Virtual Machine to a Virtual Network subnet, you would create a Network Interface, associate it with the subnet, and then associate the Network Interface to the Virtual Machine's "network profile."