A. There have been a number of evolutions of Hyper-V terminology, but the correct term for the server with the Hyper-V role enabled is the root partition. Other names for the root partition have been "host" and "parent." Microsoft employees and the current Microsoft Hyper-V page  say that the correct term for a VM running on Hyper-V is guest partition. Other names for guest partitions have included "child" and "VM."

See also:
Where can I download the Microsoft Hyper-V 1.0 final release?
Why can't I take a Hyper-V snapshot of a virtual machine (VM) that has a pass-through disk configured?
How can I quickly connect to a Hyper-V Server's child partition?
Hyper-V: The Good, the Bad, and the Ugly



Videos:
Understanding and Using Hyper-V Server
Virtualization and Hyper-V Architecture Fundamentals
Hyper-V Networking
Hyper-V Performance




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