Using Install-WindowsFeature with Offline Source
As you probably know, the Install-WindowsFeature (used to be Add-WindowsFeature; that’s now an alias to Install-) can add Windows roles and features from PowerShell. If your server doesn’t have the installer source on the local disk, then the cmdlet will default to grabbing it from Windows Update - a pain for disconnected servers. Install-WindowsFeature does offer a means of using an alternate local source (like a DVD or file server location), but using it can be a bit hinky.