Do DSLRs have digital zoom?

I'm purchasing the Nikon D5100 (kit lens included) and would like to know if it can zoom digitally possibly.

No, you zoom and crop later in editing software.

Digital zoom is one of those marketing tools to make a P&S sound better than the competitor.

The only thing you want to use on any camera is optical zoom and in the case of DSLRs, that all depends on the lens that you put on the camera.

No. The only zoom on a DSLR is the lens - 18-55mm, 70-200mm, 80-300mm etc.

With an editing program you can enlarge part of an image file which is called "cropping" but you'd better have as perfect an image file as possible. So always shoot at your camera's highest resolution at a low ISO like 100 and be certain focus and exposure are perfect.

Digital zoom means lack of details. So why you are interested in digital zoom when your dslr can give you optical zoom of infinity (with proper lens)