What should you use to configure the default route?

You need to configure the default route in Vnet2 and Vnet3. The solution must meet the virtual networking requirements.

What should you use to configure the default route?
A . a user-defined route assigned to GatewaySubnet in Vnet2 and Vnet3
B . a user-defined route assigned to GatewaySubnet in Vnet1
C . BGP route exchange
D . route filters

View Answer

Answer: A

Explanation:

To configure the default route in Vnet2 and Vnet3 according to the scenario provided, the best approach would be to use User-Defined Routes (UDRs). A UDR allows you to override Azure’s default system routes or to add additional routes to a subnet’s route table. In this scenario, you want to direct the default route (0.0.0.0/0) from Vnet2 and Vnet3 to the Boston datacenter over an ExpressRoute circuit, which is a typical use case for UDRs.

Here are the options:

Option A (a user-defined route assigned to GatewaySubnet in Vnet2 and Vnet3): This would be the correct approach. You can create a UDR for the default route (0.0.0.0/0) and apply it to the GatewaySubnet in both Vnet2 and Vnet3. This will ensure that all traffic destined for any address not within the local VNet or any peered VNets will be routed to the Boston datacenter via the ExpressRoute circuit.

Option B (a user-defined route assigned to GatewaySubnet in Vnet1): This is not correct because we need to configure the default route for Vnet2 and Vnet3, not Vnet1. Changing the routing in Vnet1 doesn’t directly affect the routing behavior of Vnet2 and Vnet3.

Option C (BGP route exchange): While BGP (Border Gateway Protocol) is used in Azure for route exchange, especially in scenarios involving ExpressRoute, simply relying on BGP without defining specific routes may not guarantee that the traffic will be routed according to the specific needs of this scenario.

Option D (route filters): Route filters are used in Azure to enable access to Microsoft peering service communities. They are not used for defining specific routes within a VNet.

Therefore, the correct choice for configuring the default route in Vnet2 and Vnet3 is A: a user-defined route assigned to GatewaySubnet in Vnet2 and Vnet3. This approach directly addresses the requirement to direct all traffic from these VNets to the Boston datacenter over the ExpressRoute circuit.