A financial services firm wants all internet-bound traffic from VMs in a spoke VNet to be routed back to their on-premises security stack (forced tunneling) over an existing Site-to-Site VPN. Which Azure configuration pattern will accomplish forced tunneling while preserving route propagation from the VPN connection?

The correct option describes the standard and recommended method for implementing forced tunneling over a Site-to-Site VPN in Azure while maintaining route propagation. A UDR with 0.0.0.0/0 pointing to the virtual network gateway ensures all internet-bound traffic from the spoke VNet is directed to the gateway. For the gateway to then forward this traffic to the on-premises network, the on-premises router must advertise a default route (0.0.0.0/0) via BGP to the Azure VPN gateway. This allows the gateway to learn the route and propagate it to the spoke VNet. Azure Firewall's forced tunneling feature is for directing traffic to Azure Firewall, not directly to an on-premises VPN gateway. Configuring the gateway to rewrite IPs and send traffic directly to the internet is not forced tunneling to on-premises. Adding a DNS suffix only affects name resolution, not routing of IP traffic.