Are all Nikon Lenses compatible to all Nikon Cameras?

I'm going to buy a Nikon D5100

Not entirely;

Pre AI lenses will damage your camera

AI and AIS lenses will fit, but won't allow your exposure meter to work. Like pre-AI, these lenses can't autofocus.

AF lenses (and third-party equivalents) will allow metering, but not autofocus.

AF-S lenses (with motors) and their third-party equivalents allow full functionality.

The D5100 normally comes with an 18-55mm AF-S lens - by the time you build up enough experience to need a second lens, you'll probably be better able to work out what you need.

ALL AF-S lenses will work perfectly well on a Nikon D5100, whether they are DX or FX lenses. Later if you do buy a full frame Nikon D600, your old lenses will work perfectly fine on any full frame camera

The older legacy Nikon AF lenses will work, but as with any entry level Nikon cameras, you will need to use the electronic rangefinder in the viewfinder. Eventually all Nikkor lenses will be AF-S lenses, so buying a legacy AF lens will not be a problem. Why, because the AF-S lenses auto-focus much faster than the old AF lenses and Nikon is methodically updating all their older AF lenses

If you want to be able to use ANY Nikkor lens, from manual focus AI lenses from the 1980's, you will have to step up to the Nikon D7000 or D7100

Here is a complete, mind boggling list of all Nikkor lenses and the cameras that can use them.

http://www.kenrockwell.com/...y-lens.htm

All lenses but IX-Nikkor and F3AF lenses will "work" on your camera. These two types that will not were some esoteric "experiments" Nikon did in the past.

However, only "AF-S" lenses will autofocus on the D5100. "AF" lenses will mount on your camera and meter properly, but you will not have the ability to autofocus them. If you have a desire for AF lenses, you need a D7000 and above.