Adding features to Windows Server 2012 without an Internet Connection

If you have not already discovered this yourself, Windows Server 2012 employs a new "Feature on Demand" installation for Adding Features through Server Manager.

What this essentially means is that the default installation scenario connects to Windows Update over the Internet to download and install server features.

Well, if your environment does not have Internet connectivity, the installation simply fails out without any warning or indication of the underlying failure (especially if you are trying to do this through PowerShell).

Here are some more details on exactly how this works: http://blogs.technet.com/b/askcore/archive/2012/05/14/windows-8-and-net-framework-3-5.aspx

Of course, if you just working directly with Server Manager, you can simply specify the Alternate Source Path during the feature installation wizard:

In my scenario, I simply pointed to the Windows Server 2012 ISO Image media as my alternate source path.

If you are using a VM, it might be easier to simply have a "permanently mounted" ISO image for Windows Server 2012 to avoid copying it over to the local HDD on the VM and wasting valuable space.  An easy workaround is to simply add another CD/DVD virtual device to the VM and use that instead for any other ISO image installation media while the primary CD/DVD virtual device is mapped to the Windows Server 2012 installation media.