For some reason Microsoft appears to have messed up the install media manifests or something because the components required to install DotNet 3.5 are copied to the local disk so you can add them as a feature post-install. I don’t know if there are other features that have this problem, but I haven’t come across them yet if there are.
So, to install DotNet 3.5 is actually pretty easy. You will need your Install DVD, or an ISO, or a copy of the files from the DVD somewhere.
- Open the wizard to “Add Windows Features”
- Select the .NET Framework 3.5 Features
- On the Confirmation screen, click the “Specify an alternate source path” link
- Set the path to “D:\sources\sxs” where D: is you DVD media drive, or the path to wherever your install media files are
- Click next and finish the wizard to complete the install
Or, if you want a messy command line driven method, here’s a plug for Daves blog on the hard way to do it: