The origin of the name is old nordic Norðbýr, 'north-farm'.(ref Store Norske Leksikon)
Used for several different farms in the Nordic countries, as Nordby, Fanø, (Southern) Denmark (Wikipedia), Nordby, Ås, Akershus, Norway (SNL), Nordby, Aurskog, Akershus, Norway.
A complete list of the Norwegian Nordby farms.