DHCP and Private Virtual network = APIPA (Hyper-V 2012)

I have a Desktop on which 2012 has been installed.

This desktop has no network and i prefere to remain it that way since it is only used for testing purposes.

So i've created some VM into a Private network but none of the VM does receive any valid ipadress.

Who provides ipadresses when the Private network is choosen ? and how can it be setup ?

Thanks for your help.