[Podcast] ‘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. Over time, this number has changed, as DNS protocol usage has changed. We now have DNS records that didn't exist when the problem was first seen, and therefore have multiple queries about multiple things.

Geoff has been exploring two aspects of DNS. Firstly, he examines how different ways of answering 'no' affect query volume, as well as the amount of work required by authoritative servers, intermediate resolvers, and clients. The results are sometimes surprising, with different ways of saying no, including not responding at all, leading to very different outcomes.

Secondly, he explores the impact that alternative DNS transport protocols could have on query repetition and overall query load, which may in part be a consequence of User Datagram Protocol (UDP) and its behaviour. Many have argued that the overhead of maintaining connection state for TCP and similar protocols made them unsuitable for DNS at scale. However, as the volume of unnecessary repeated queries continues to grow, it is possible that, end-to-end, maintaining protocol state may actually require less work than repeatedly handling the same queries.

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