On May 1, 2020, at 22:22, Geoff Huston <gih@apnic.net> wrote:
On 2 May 2020, at 1:25 am, Dave Lawrence <tale@dd.org> wrote:
Geoff Huston writes:
"Finally, many more resolvers today are capable of falling back to TCP when they receive a truncated response over UDP”
really? Where is the study that publishes this finding?
It could use clarification, certainly, beyond just the fuzziness of "many more". There are several metrics which could all claim to be relevant. A few of them seem like they are probably true in raw numbers if only because of overall growth over the past couple of decades (and yes, good measurement would confirm that). Like:
* Total number of implementations * Total number of running servers * Total number of people served (not strictly a resolver, but still relevant)
But, maybe that picture changes when you ask about the percent of the whole, and then "many more" might not apply.
Measurement rules, for sure. I also don't think it is entirely out of place to make a qualified claim based on our cumulative anecdotal experience that overall the TCP fallback scenario is improved now vs the past, as long as it clear that it is supposition rather than data.
My measurements of TCP use from time to time report that the relative number of users that sit behind recursive resolvers that cannot perform TCP appear to be unchanged for the 6 years that I’ve looked (from time tim time). Now there are many ways of reporting DNS (resolvers, users, queries, … as well as absolute numbers or relative numbers).
Therefore I don't understand the basis of the TCP claim in that report - it seems apocryphal to me
I’ve deleted that sentence from the answer to question 1. The answer no longer makes any statements regarding how many resolvers can fallback to TCP if UDP comes back truncated. —Andrew