Azure Virtual Network deployment provides enhanced security and isolation for your Azure Cache for Redis, as well as subnets, access control policies, and other features to further restrict access.When an Azure Cache for Redis instance is configured with a virtual network, it is not publicly addressable and can only be accessed from virtual machines and applications within the virtual network.
Use Azure ExpressRoute or Azure virtual private network (VPN) to create private connections between Azure datacenters and on-premises infrastructure in a colocation environment. ExpressRoute connections do not go over the public internet , and they offer more reliability, faster speeds, and lower latencies than typical internet connections. For point-to-site VPN and site-to-site VPN, you can connect on-premises devices or networks to a virtual network using any combination of these VPN options and Azure ExpressRoute.
To connect two or more virtual networks in Azure together, use virtual network peering or Private Link. Network traffic between peered virtual networks is private and is kept on the Azure backbone network.
What are the ExpressRoute connectivity models: https://docs.microsoft.com/azure/expressroute/expressroute-connectivity-models
Azure VPN overview: https://docs.microsoft.com/azure/vpn-gateway/vpn-gateway-about-vpngateways
Virtual network peering: https://docs.microsoft.com/azure/virtual-network/virtual-network-peering-overview
Azure Private Link: https://docs.microsoft.com/azure/private-link/private-link-service-overview