A GeoNexus proximity network provides quick determination of proximity of a large group of associated mobile devices (e.g., ‘friends’, all devices associated with those who ‘like’ a given posting, etc.) To respond to a given proximity request, a list of identities is obtained for the group of associated mobile devices for which proximity is to be determined. A bucket index is determined of a place to which proximity is to be determined for each of the plurality of associated mobile devices. A target geonexus node associated with the determined bucket index is queried, which in turn queries geonexus nodes adjacent thereto, to quickly determine which of the group of mobile devices are proximate, without the need to individually query for location of each mobile device in the group.