Join 2012 R2 Server to 2003 Domain

If you're wanting to promote a 2012 R2 server to be a Domain Controller in a 2003 domain, you'll need to run adprep.exe from the 2012 R2 ISO to update the AD schema.

See this blog for more detail: http://support.risualblogs.com/blog/2013/10/25/wmi-error-when-adding-a-server-2012-r2-domain-controller-to-existing-2012-domain/

Clear Skype for Business or Lync Temporary Cache Files

Follow instructions here: https://www.cosocommunity.com/hc/en-us/articles/200887737-How-to-Clear-Lync-Temporary-Cache-Files

In path for the location where temp files are stored, use \%AppData%\..\Local\Microsoft\Office\16.0\Lync\ for SfB.
use \%AppData%\..\Local\Microsoft\Office\15.0\Lync\ for Lync.