There's a rumour that public domain name resolvers, like Google Public DNS, are still supposed to work with GeoDNS, because there's some field in the requests that lets them specify for which IP address they are doing a resolution, thus the authoritative servers can give a given resolver different resolutions for different final clients.
What's this whole thing called as far as RFCs go, and how does one mimic such resolutions, for testing purposes, e.g. with dig(1)? Else, what other tool is available to accomplish said task?
