You manage an Azure virtual network that hosts 15 virtual machines (VMs) on a single subnet, which is used
for testing a line of business (LOB) application. The application is deployed to a VM named
TestWebServiceVM.
You need to ensure that TestWebServiceVM always starts by using the same IP address. You need to achieve
this goal by using the least amount of administrative effort.
What should you do?

A.
Use the Management Portal to configure TestWebServiceVM.

B.
Use RDP to configure TestWebServiceVM.

C.
Run the Set-AzureStaticVNetIPPowerShell cmdlet.

D.
Run the Get-AzureReservedIP PowerShell cmdlet.

Explanation:
Specify a static internal IP for a previously created VM
If you want to set a static IP address for a VM that you previously created, you can do so by using the following
cmdlets. If you already set an IP address for the VM and you want to change it to a different IP address, you’ll
need to remove the existing static IP address before running these cmdlets. See the instructions below to
remove a static IP.
For this procedure, you’ll use the Update-AzureVM cmdlet. The Update-AzureVM cmdlet restarts the VM as
part of the update process. The DIP that you specify will be assigned after the VM restarts. In this example, we
set the IP address for VM2, which is located in cloud service StaticDemo.
Get-AzureVM -ServiceName StaticDemo -Name VM2 | Set-AzureStaticVNetIP -IPAddress 192.168.4.7 |
Update-AzureVM

http://msdn.microsoft.com/en-us/library/azure/dn630228.aspx