Offline install for .Net 3.5 SP1 on Windows 2012

when I try to install .NET 3.5  from Server Manager on Windows Server 2012, I get the following screenshot:

Does that mean I can't install it ?

Answer is sure NO !

you can simply install it offline in 2 steps:

1- open the CMD (run as administrator)

2- type  the following command

Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:d:\sources\sxs /LimitAccess

where D: represent windows 2012 source drive.

Reference