How to sync the clock of DomainControllers that are running as child VM in HyperV2012R2

I've a domain controller that is running as virtual machine.
Domain name: test.local
DomainControllerName: PDC.test.local

The parent server has Windows Server 2012 R2, with HyperV Role.
It is member of domain test.local, and it's hostname is: parent.test.local

Now i want to know how to synchronize the clock of DC with internet NTP Servers??
what about the time synchronization in settings of virtualmachine, have i to leave them default as checked, or i've to uncheck??
Regards!

Lasandro Lopez