How to enable .NET Framework 3.5 on Windows
8 in Offline Mode

The following are the steps to enable .NET Framework 3.5 (include .NET 2.0 and 3.0) feature in offline mode :
 

Step 1 :
Insert Windows 8 DVD or mount ISO image. The source of this feature can be found in folder E:\sources\sxs. (In this case E: the user’s drive letter on which the user
has loaded Windows 8 Media.)

 

Step 2 :
Open CMD.EXE with Administrative Privileges.
 

Step 3 :
Run the following command Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:E:\sources\sxs /LimitAccess, and hit Enter.
After completing the installation of .NET Framework 3.5 you can see that the feature is enabled.