Long story short, Microsoft has decided not to include .NET Framework 3.5 in Windows 8 since the Preview days. It is not a secret now and its a child's play to install it. Anyway I have decided to post all the available methods and their sources (time pass :D).
- Most of us decide to take the easy route aka install it though Programs and Features (via Windows Update).
- The famous canouna/NTmarta@MDL had posted the dism way on 03 October, 2011(!). Seems that Microsoft didn't want to spread this fact then, so it was distributed with a 'CONFIDENTIAL' tag.
- Both ways (through Windows Update and dism) are discussed in MSDN.
- Some people prefer the reverse integration method i.e install it online/offline, then capture the installation to a WIM and later use the WIM for further installation.
- Dr.Emuler@MDL has decided to make an offline installer where the resources are embedded in it and it doesn't need Windows Installation media. It is revised and currently maintained by abbodi1406@MDL (for 8.1, see here).
- AskVG reader Cedric Poottaren has made a GUI front end of the dism way.
- One VBScript and one PowerShell script are published in Technet. Both cover the online & offline ways.