In my lab I tend to spin up loads of Windows Server 2012 R2 servers to test various things. One thing that always causes me frustration is having to manually point the \sources\sxs folder when installing a new Server Role, via Server Manager or PowerShell. Its frustrating because I normally forget to do it, and the installation fails and I need to start again.
To configure a network based copy of the SXS folder and have it automatically mapped via GPO, first copy the \sources\sxs folder from the DVD media to somewhere you can share the folder from. Then configure the share and NTFS permissions, I have allowed Full Control to Everyone on the share permissions, and Full Control to Domain Computers on the NTFS permissions.
As I want this setting to be global across the domain I am going to put the setting in the Default Domain Policy open the GPMC and edit the GPO you want to host the settings.
Expand Computer Configuration/Policies/Administrative Templates/System and double click on the policy Specify settings for optional component installation and component repair.
Click the Enable button and enter the UNC path to the SXS folder you copied over, if the access permissions are not configured correctly this obviously will not work. Click Apply and OK.
Now when you try to install Server Roles or Features via Server Manager or PowerShell the machine will have a known location for the required binaries.