On a cropped sensor like the 5100 this will shoot like a 75mm lens on an old school 35mm film camera. It could take decent pictures of real estate. The 35mm fixed lens is also a low price and would be wider. The 55mm and the 35mm f1.8 lens are the best bargains once you get past the kit lens.

With a fixed lens you need to get out of the car and walk more. With the kit lens like the 17-55mm zoom you wouldn't. The kit len won't stop down as low so you'll need better light but then you don't shoot properties in poor light in any case. They need to look nice! Nothing beats better light.

The 17-55mm would do interior shots better and you could shoot at a high ISO and still not need a flash in decent light. For a realtor the kit lens might just serve more situations. You just wouldn't want to shoot in poor light in any case since you want a pretty bright picture. Stepping up to a Prime zoom lens might be better but would cost a LOT more and maybe not pay off for web based images. The 5100 can jump through lots of hoops and then some. Shooting raw images you can do far more than you could ever need. Even in auto mode the 5100 is an amazing camera.