Virtual Network NAT provides NAT gateway resources for on-demand outbound connectivity without complex pre-planning. You can also simplify whitelisting by configuring one or more subnets of your virtual network with a NAT gateway resource. Once set up, all your virtual machine instances have outbound connectivity and use your specified static IP addresses. The outbound source IP addresses can be public IP address resources, public IP prefix resources, or a combination of both. Outbound connectivity is possible without load balancer or public IP addresses directly attached to virtual machines.

Microsoft Azure provides a 99.9% uptime SLA for NAT gateways.