[andrewcooke]

what he (i assume?) is saying is that when a cdn wants to supply data to you, they want to do so from a server as close as possible.

now, typically, dns is configured so that your dns requests go to servers that are "near" you on the network.

so, say you're looking for google.com. the dns server near you will be configured to say that google.com is a server near you (and near the dns server). effectively they are inferring location from dns lookups (and then providing you with a nearby source).

this is completely different to looking up the requesting ip in a database which is what i originally assumed was being discussed (hence my confusion and perhaps yours). but it (this process for choosing cdn providers) does seem to be called geolocation by cdn people (just google "cdn geolocation").