Answer: You cannot do NFS export on windows 2012.
Microsoft supports network-attached storage (NAS) for Hyper-V in Windows Server 2012 when using SMB 3.0. NFS-based storage is not supported.
The only supported shared storage on Hyper-V cluster with windows 2012 are:
1. Fibre Channel (FC) SAN Arrays
2. iSCSI SAN Arrays
3. SAS JBOD Enclosures with SAS Expanders
4. SMB 3.0 Shared Folders on a Windows Server 2012 file server or, preferably, by a Windows Server 2012 clustered file services role for continuous storage availability.
Just out of interest are you looking to present NFS to Hyper-V not sure you can store your VM’s on NFS exports under hyper-v, you can present SMB3 shares to Hyper-V (not currently supported in ONTap but will be in OnTap 8.2) to host VM’s, but don’t think you can with NFS.
What are you hoping to achieve?