Windows Azure IP Address

Windows Azure is having Private IPs and Public IPs:

Private IPs : Private IPs are defined in a specific range.

10.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255

Publics IPs : Public IPs are defined through Region / data centers. It allows you to map to the IPs based on which Windows Azure Service you are going to use.

There are possibly 4 scenarios to consider:

1. Web Role / Worker Role

Azure service has its own load balancers. Since you have defined your own VIP, all instances like single instance or multiple instance will share the same virtual IP address. This IP address will remain with the instance till the deployment of role is hosted on Windows Azure.

2. VM in a cloud Service

Azure can have multiple virtual machines. These machines do not share the load-balancers endpoints. Buts these machines are the part of the same cloud service. They have the single public IP.

3. VM on a Virtual Service

Virtual Machines which are deployed to the Virtual Networks still have the cloud services.  The IPs are differentiated based on URL,

http://www.windowsazure.com/en-us/manage/services/networking/add-a-vm-to-a-virtual-network/

4. VM on a virtual network with site-site VPN

The Virtual network is routed through the VPN. This gives us better security whenever the call is made and is routed through the corporate firewall. It enables access to on-premises addresses. With the  VPN, the virtual Azure should be treated more or less exactly any other virtual server on the corporate network.