Q:

Install Net 3.5 Framework on Windows Server 2012 without DVD

I am trying to enable Net 3.5 Framework on Windows Server 2012. However, all the instructions I find on the Internet say I must have DVD of Windows Server 2012.
http://en.community.dell.com/techcenter/os-applications/w/wiki/4146.installing-net-3-5-framework-on-microsoft-windows-server-2012.aspx
Since I do not have DVD I have been searching for where to download this feature.
Thanks in advance

A:

To install the .net 3.5 on server 2012 without the disk (or disk image):

Ensure that the server is NOT looking at a WSUS server for updates (must be looking at Windows Update for this to work)
Ensure that any proxy/firewall will allow the connection from the server in question to the Windows update service
From a command line run:
dism.exe /online /enable-feature /featurename:NetFX3 /all

The elimination of the source switch is done on purpose as this will force the server to look within its own SxS folder, not find the needed files, and then go to Windows Update for the files (hence step 1 where it is not pointing to a WSUS server).

A:

You can configure server to use Windows Update as a source for for optional components installation. And then install .NET 3.5 through the Add Roles and Features Wizard.
You can configure server by registry: 
[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Servicing]
"RepairContentServerSource"=DWORD(2)

or by Group Policy:
Computer Configuration -> Administrative Templates -> System
"Specify settings for optional component installation and component repair"

found here: 
https://www.404techsupport.com/2012/11/server-2012-you-must-use-the-role-management-tool-to-install-or-configure-microsoft-net/
https://msdn.microsoft.com/en-us/library/windows/desktop/hh848079(v=vs.85).aspx?ppud=4&tduid=(ad1620201cdb131ba52a8e05b8ffef0c)(256380)(2459594)(TnL5HPStwNw-mxEPD8HDp4sXn1EnYFo1cA)()

