Load balance your Azure virtual machines with private IP addresses. If your VM is in a virtual network, the internally load-balanced endpoint is accessible there. If it isn't, you can access it using a cloud service. Internal load balancing is useful when you’re creating multi-tier applications, and you want to load balance application tiers that aren't public facing. It's available in the VM standard tier at no additional cost.
For more information, visit the Internal Load Balancing