What EXIF program are you using to extract the information? I've never seen EXIF look like that!
I use Flickr and saw most of the Nikon D3100 user exif data loooks like that in Flickr where it says unknown colour balance.
So why is it important for you to know? If it says that for all the 3100, then maybe it's the way it is. I say just go out and use your camera, be creative and let numbers be.
Well I have not stopped to take photos and I am using my camera. Just to know why is it there as it is important to me. Camera is not a magical or heavenly object that makes a person creative. It's technical side needs to be understand to be creative. So still if anyone of you know please let me know.