Our web system, use the third-party cdn service. Assume that the user set the local dns with the googledns or opendns to visit our web sites, so cdn service will select the closest cdn proxy node. all right, but in fact the user's actual access position might outside there, cdn service may chose the one furthest away from the user node, so static resource access slower..

At present, my idea is if user local set dns server with googledns, and then first one we get the actual ip address of the user, tracerote to test a best routing lines, set up a cookie in user browser, and then set 302 header for response to jump to the which best cdn node.

Whether the user's browser side traceroute tool can provide the best route decision-making ?

Because we find that, once the user to set local dns server with the foreign network segment, for example : set dns with 8.8.8.8, so cdn routing will choose the foreign service node.