Move External IP Address from On-Premises to Azure

Q: How can I take an external IP address from my organization and use it in Azure?

A: If you publish services from on-premises to the Internet, you likely do so by having a publicly accessible IP address and a public DNS entry that resolves to that IP address. If you move this service to Azure, perhaps as part of a failover, your first thought might be to take this IP address to Azure; however, this isn't possible. The virtual IP address (VIP) used for cloud services and even for instance-level IP addresses comes from the Azure pool of IP addresses. There's no way to suddenly make your on-premises IP address assigned from your carrier route correctly to Azure services. An alternative solution is to use one of the following approaches:

Likewise, you can't use an Azure VIP on-premises. The IP address wouldn't route correctly.