Case study (Litware): Vnet1 is peered bidirectionally with Vnet2 and Vnet3. Vnet2 and Vnet3 must communicate via Vnet1, meet the virtual networking and business requirements (including routing default 0.0.0.0/0 from Vnet2 and Vnet3 to on-prem via ExpressRoute), and minimize costs. Which two changes should you apply to the peerings to allow Vnet2 and Vnet3 to communicate through Vnet1? (Choose two.)

To allow Vnet2 and Vnet3 to communicate through Vnet1, Vnet1 must act as a transit network. The option "On the peerings from Vnet2 and Vnet3, set 'Use the remote virtual network's gateway or Route Server'" enables Vnet2 and Vnet3 to use Vnet1's gateway (or Route Server) for routing traffic, including to each other. This is crucial for transitive routing. Additionally, "On the peerings from Vnet2 and Vnet3, enable 'Allow' for Traffic forwarded from remote virtual network" permits Vnet1 to forward traffic originating from Vnet2 to Vnet3, and vice-versa, which is necessary for the communication to occur. The other options are incorrect because enabling 'Allow' for Traffic forwarded from remote virtual network on Vnet1's peering would allow Vnet1 to forward traffic from Vnet2 to Vnet3, but doesn't enable Vnet2/Vnet3 to use Vnet1 as a transit. Setting 'Use the remote virtual network's gateway or Route Server' on Vnet1's peering would mean Vnet1 uses Vnet2's or Vnet3's gateway, which is not the desired transit scenario.