When deploying route-based site-to-site VPN connections from multiple on-premises locations to an Azure virtual network, which tunneling protocol should you use?

IKEv2 (Internet Key Exchange version 2) is the correct tunneling protocol for route-based site-to-site VPN connections in Azure, especially when connecting multiple on-premises locations. Azure VPN Gateways primarily use IKEv2 for route-based VPNs due to its enhanced security, reliability, and support for features like MOBIKE (Mobility and Multihoming Protocol) which improves connection stability. IKEv1 is an older version with fewer features and is less secure. PPTP (Point-to-Point Tunneling Protocol) and L2TP (Layer 2 Tunneling Protocol) are older, less secure protocols primarily used for point-to-site VPNs or specific legacy scenarios, and are not recommended or supported for route-based site-to-site VPNs in Azure.