DRAG DROP
Your network contains an Active Directory domain named contoso.com. The domain
contains multiple servers that are configured as Hyper-V hosts.
You plan to implement four virtual machines. The virtual machines will be configured as
shown in the following table.
You need to identify which network must be added to each virtual machine.
Which network types should you identify?
To answer, drag the appropriate Network Type to the correct virtual machine in the answer
area. Each Network Type may be used once, more than once, or not at all. Additionally, you
may need to drag the split bar between panes or scroll to view content.
Answer: 
Explanation:
http://blogs.technet.com/b/jhoward/archive/2008/06/17/hyper-v-what-are-the-uses-fordifferent-types-of-virtual-networks.aspx
An external network, which provides communication between a virtual machine and a
physical network by creating an association to a physical network adapter on the
virtualization server.
An internal network, which provides communication between the virtualization server and
virtual machines.
A private network, which provides communication between virtual machines only.
http://technet.microsoft.com/en-us/library/cc732470%28v=WS.10%29.aspx