I'm having issues specifically with Windows 2012 R2 operating systems not dynamically registering their network information in my DNS.
My AD/DNS environment consists of Windows 2008 R2 and Windows 2012 R2 Domain controllers in a 2008 R2 Functional Domain/Forest.
Windows Server 2003, Windows Server 2008, Win 7/R2, Server 2012, and Windows 8.1 VM/physical are registering DNS dynamically for both DHCP received address as well as statically assigned addresses.
Windows 2012 R2 is generally running on Gen2 VMs in a 2012R2 host, but the problem exists with the 2012 R2 physical hosts as well.
Manually registering via ipconfig /registerdns works. DNS scavenging is in place, 1 day / 1 day.
To summarize - its working for everything else dynamically, but just not for Windows 2012 R2 DHCP/Static networking information.