Which Azure networking service enables secure VNet-to-VNet communication over the Microsoft backbone?

VNet Peering is the correct answer because it directly connects two Azure Virtual Networks (VNets) within the same or different regions, allowing them to communicate securely using the Microsoft backbone infrastructure. This connection is private and uses internal Microsoft networking, not the public internet. ExpressRoute is incorrect because it connects your on-premises network to Azure, not VNet to VNet. While it uses the Microsoft backbone, its primary purpose differs. VPN Gateway is incorrect because it typically establishes secure connections over the public internet (site-to-site or point-to-site VPNs) or can be used for VNet-to-VNet, but VNet Peering offers a more direct and often preferred solution for VNet-to-VNet within Azure. Azure DNS is incorrect as it is a DNS hosting service for name resolution, not a service for connecting virtual networks.