Hyper-V: Configure the server with a sufficient amount of dynamic MAC addresses

Applies To: Windows Server 2008 R2, Windows Server 2012

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the Hyper-V Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer.

Operating System

Windows Server 2012 or Windows Server 2008 R2








The number of available dynamic MAC addresses is low.


When no dynamic MAC addresses are available, virtual machines configured to use a dynamic MAC address cannot be started.


Use Virtual Network Manager to view and extend the range of dynamic addresses.

You can use Virtual Network Manager to specify a range of media access control (MAC) addresses to assign to virtual machines, as well as to constrain the range of dynamic MAC addresses. When more than one physical computer running Hyper-V uses the same subnet, avoid duplicating the same address range on more than one of the physical computers to prevent potential conflicts that would result if the same MAC address is assigned to more than one virtual machine on the subnet.

By default, membership in the local Administrators group, or equivalent, is the minimum required to complete this procedure. However, an administrator can use Authorization Manager to modify the authorization policy so that a user or group of users can complete this procedure. For more information, see Using Authorization Manager for Hyper-V Security (http://go.microsoft.com/fwlink/?LinkId=142886).

To view and extend the range of dynamic addresses

  1. Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.

  2. From the Actions menu, click Virtual Network Manager.

  3. Under Global Network Settings, click MAC Address Range.

  4. Review the minimum and maximum values for MAC addresses and specify new values if necessary.

  5. Click OK.