If you need to reserve static ip address for your VM, follow the commands below:
1. Set static ip:
New-AzureReservedIP -ReservedIPName "postgresql" -Location "West US"
2. Assign static ip, defined above to VM named postgresql –vm
Error, some other host already uses address. Workaround
If you receive such message on your virtual machine, you have workaround to fix this problem.