How to install .NET Framework 3.5 on Windows Server 2012

inI am currently working on a project of installing System Center Configuration Manager 2012 on a Windows Server 2012 infrastructure. Yesterday, I ran in to a problem when trying to install SQL Server 2008 R2. The problem was that the .NET Framework 3.5 was a requirement, and I was unable to install it from the Server Manager.

This is the problem I ran in to when trying to add the feature:
“Do you want to specify an alternate source path? One or more installation selections are missing source files…”

Apparently, there’s a bug in Windows Server 2012 when trying to add the .NET Framework 3.5 from Server Manager. In order to get it to work, I had to enable the feature via the Command Prompt.
This is the command that I had to type:
dism /online /enable-feature /featurename:NetFX3 /all /Source:d:\sources\sxs /LimitAccess
Note: Source should be the Windows installation disc. In my case, this was located on D:

After running this command, .NET Framework 3.5 was enabled and I was able to install SQL Server 2008 R2