Q: What is the purpose of the new DHCP guard feature inHyper-V? How should I use this new feature?
A: DHCP guard is a new property in Server 2012 Hyper-V that you can configure for each network adapter in a virtual machine (VM). When DHCP guard is enabled, it prevents a VM from acting as a DHCP server. If a VM attempts to send a packet that indicates it's a DHCP server, the packet will automatically be dropped.
Related: Using the Hyper-V DHCP Guard Feature
You can enable DHCP guard using Server 2012 Hyper-V Manager. In the VM's properties, go to the Network Adapter settings and click Advanced Features. Select the Enable DHCP guard check box, as Figure 1 shows. I recommend that you enable this setting during the creation of your VM golden image. That way, it's enabled by default for all new VMs you create from that image.