Enable .NET 3.5 feature, Server 2008, command line

I am now playing with very original windows 2008 r2 iso image:
en_windows_server_2008_r2_with_sp1_x64_dvd_617601.iso

8dcde01d0da526100869e2457aafb7ca

d3fd7bf85ee1d5bdd72de5b2c69a7b470733cd0a

In a fresh Windows Server 2008 R2 installation there is no .NET 3.5 installed.
It is possible to query all .NET versions in registry by looking under:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP

To install .NET 3.5.1 from command line open command prompt in "Run As Administrator" mode and execute:

dism /online /enable-feature /featurename:NetFx3

That is it. One command. 10 seconds and i got it:

If i miss the case of feature name then i get error 0x800f080c.
So it is better to write NetFx3 and NOT netfx3:

At the end i make sure that .NET 3.5 is finally installed: