Windows Server 2012 R2 (Datacenter)
Source: MSDN (DVD 2707946)
Behaviour: try installing Microsoft .NET 3.5 from add roles and features with NO internet connection
Typical Message: feature not present, specify alternate location
Specifiy DVD Drive\Sources\Sxs\
Installation failed: no sources found
Then connect to internet, do same steps, installation goes like a charme
Anybody experiencing same issue ?