Q: Does the virtual RSS feature in Windows Server 2012 R2 Hyper-V work with a Windows Server 2012 guest?

A: Windows Server 2012 R2 Hyper-V features virtual RSS (vRSS) for Windows Server 2012 R2 and Windows 8.1 guest OSs, which allows Receive Side Scaling for inbound network traffic--useful for very large network connections such as 10Gbps.

The vRSS functionality is not part of Windows Server 2012 and therefore won't work by default. However, if you install the Windows Server 2012 R2 Hyper-V Integration Services within the guest OS when running on Windows Server 2012 R2 Hyper-V,  then vRSS will work.