The DNS server is the wrong place to make that decision. If there is a set of choices and a decision to make, letting the client choose would be the best optio

The DNS server is the wrong place to make that decision. If there is a set of choices and a decision to make, letting the client choose would be the best option. I think I'd start with a client shuffling the list of results and asking for small fragments of the dataset from each. Based on the latency, bandwidth detected, and the size of the requested data it would then pick the most optimal set of servers. This also allows for fallback in case servers are unresponsive.