A:Answer Your D3100 does not have an autofocus motor. It will require lenses that have that motor built-in. Nikon denotes these type of lenses with an AF-S (or more recently, and AF-P). Since this lens is an AF-S type lens, it does have Nikon's Silent Wave Autofocus Motor incorporated in it. It will work, with autofocus, on the D3100. Just a note, AF-P type lenses, while they contain Nikon's new Pulse AF motor, they will NOT work on the D3100.