Throughout the lifetime of a deployment, the VIP assigned will not change, regardless of the operations on the deployment, including updates, reboots, and reimaging the OS. The VIP for a given deployment will persist until that deployment is deleted.”

More Details:

  • The VIP is associated with the deployment which means it will not change even when a single instance is service healed and moved to another physical machine. 
  • Now your service will be highly available when you have 1 instance is under rebuild process while other good instances are still serving to your requests. 
  • As you may have found earlier that VIP change could add significant downtime because DNS takes a non-trivial amount of time to replicate which means even DNS access to a site may be broken if we change the VIP. 
  • VIP stability is a major factor in high and continuous availability so now you can be assure that when due to any reason your service is down, when it will be back, it will have the same IP address. This is a BIG PLUS
  • VIP will always be same as long as your service is not deleted.
  • In the end, if you don’t delete your deployment, you keep the VIP, which is both the incoming and the SNAT’d outgoing. 
  • This is a GREAT news for those, you would need to add VIP in whitelist. Previously they would need to add a certain IP address range in whitelist because it was not certain when VIP will change, however now they can add correct VIP in whitelist and be sure that as long as they will not delete the instance, their IP address will still the same.

See Announcement:

http://blogs.msdn.com/b/windowsazure/archive/2011/07/06/windows-azure-deployments-and-the-virtual-ip.aspx