DNS load balancer should randomly respond with ALL IPs - just a different order every time

[mykaul]

Instead of responding with just one IP, it should respond with all, in a different order each time.
This allows the client to do its own randomization on the data, connect to multiple nodes (backup nodes), and whatnot.
(Does require the client to be smart enough about this, go over all IPs returned as a response, etc.!)

[nyh]

This idea needs to be tested - if it has any practical advantage over the existing situation. Do clients with existing Java/Python/whatever libraries actually get the full list and not just one? Do they do anything smart with this list (like opening connections to all of them) or just stupidly take the first one in the list?

Maybe even if it doesn't work well in today's SDK we can still propose improvements, but I'm not optimistic - Amazon's AWS returns only a single result for the dynamoDB domain - not a list - so they have no incentive to support this use case.

I added a short mention of this idea in the DNS section of https://docs.google.com/document/d/1twgrs6IM1B10BswMBUNqm7bwu5HCm47LOYE-Hdhuu_8/edit.