I was installing DirSync on a Server 2012 server (in the process of doing a staged migration to Office365 from an SBS 2008 machine) and DirSync required .net 3.5. It should be easy, but when using Server Manager to install the feature, I got this error:
Do you want to specify an alternate source path? One or more installation selections are missing source files…
I followed these excellent instructions to install it:
In my case, I downloaded the ISO file and unzipped just the sources folder and modified the path.