NIKKOR 70-300mm AF LENS for D3100

Hi,

I am new to Photography. Waiting for my first SLR. Still confused between D3200 and D5100. But that is not the question here.
While browsing through 2nd hand lenses (budget issues), I came across this ad of NIKKOR 70-300mm lens. Called the guy. He told me that he has the D3100 and the problem is, his camera doesn't have "motor" so he is not able to auto focus.
I really don't know technical things about SLRs and lenses. So can anyone tell me what is the problem here? Why can't the guy auto focus? Will I be able to auto focus with this lens from D3200 or D5100?

The guy said he bought it in January this year and has barely used it. Asking price compared to it is pretty cheap. Could it be that there is some other problem and he is just making up the story? (can't trust anyone these days. can we?)

So anyways, if you have any idea what could this problem be, please let me know...

Thanks!

He wasn't lying...Check your manual

The D3000/D5000 series camera doesn't have an AF motor so if the lens you buy Doesn't have AF-S on it it will not auto focus...

To use and auto focus AF lens You need a camera with the Auto focus motor within..

Thanks for the quick reply pedroj! Saved me from spending some bucks.. If anyone has bigger cameras with motor in them, here is the link for the lens. It is in Pune, India.