Recommended hotfixes for Windows Server

A great article listing all known issues and available hotfixes for Windows Server 2012 R2 Hyper-V Network Virtualization;

KB:2974503 – Recommended hotfixes, updates and known solutions for Windows Server 2012 and Windows Server 2012 R2 Hyper-V Network Virtualization (HNV) Environments
http://support.microsoft.com/kb/2974503/

Another fantastic source of information is Hyper-V.nu that always keeps a list to the latest updates for Windows Server (Cluster and Virtualization) here; http://www.hyper-v.nu/hotfixes/