Enable .NET Framework 3.5 (include .NET 2.0 and 3.0) offline with OS DVD

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.