"Just say no" isn't as simple as you think

In this episode of PING, APNIC Chief Scientist Geoff Huston and I continue a discussion about the repeat queries Geoff sees on the APNIC Labs experiment. Across time this number has changed, as DNS protocol usage has changed. We now have DNS records which didn't exist when the problem was first seen, and we therefore have multiple queries about multiple things. Geoff has been exploring two facets of the DNS. Firstly, Exploring the effects how you answer "NO" has on the amount of queries you see, as well as the amount of work that has to be done by authoritative server, intermediate resolvers in the chain and the client. There are some surprising outcomes in the various choices of how to say no, including simply not answering. Secondly, what impact would adoption of alternative DNS transports have on the repeats and query load, which may be a function of the UDP protocol and it's behaviours. Many people believe the overhead of maintaining TCP and related protocols in terms of state on the server was a reason to avoid it, but with the volume of uneccessary repeats rising, it is possible there is less work end-to-end, maintaining state for a protocol like TCP.