What should you do from the Azure portal before you create the ExpressRoute are the VPN gateway?

You plan to connect a virtual network named VNET1017 to your on-premises network by using both an Azure ExpressRoute and a site-to-site VPN connection.

You need to prepare the Azure environment for the planned deployment. The solution must maximize the IP address space available to Azure virtual machines.

What should you do from the Azure portal before you create the ExpressRoute are the VPN gateway?

Answer: We need to create a Gateway subnet

Step 1:

Go to More Services > Virtual Networks

Step 2:

Then click on the VNET1017, and click on subnets. Then click on gateway subnet.

Step 3:

In the next window define the subnet for the gateway and click OK

It is recommended to use /28 or /27 for gateway subnet.

As we want to maximize the IP address space we should use /27.

References:

https://blogs.technet.microsoft.com/canitpro/2017/06/28/step-by-step-configuring-a-site-to-site-vpn- gateway-between-azure-and-on-premise/