[fanf2]

I deployed DNS-over-TLS on Cambridge University’s central recursive DNS servers last week, and they immediately started receiving traffic from Android P users - not very much traffic, a few queries per second, but not negligible. I did some followup investigation of how Android behaves in the wild and posted them to the IETF DoH list (and the dprive list but for some reason those copies did not go through) - see https://mailarchive.ietf.org/arch/msg/doh/I-ytiO6ykbt9krrC9F... and the corrections and further information in the replies.

I still need to verify that TCP fast open is working, to minimize the DoT latency.

[amaccuish]

Is there a new dhcp option to indicate availability, or is it opportunistic, when the device notices port 853 is open?

[fanf2]

Android 9 Pie is opportunistic: it tries to connect to port 853 and sends a probe query to make sure the server behaves plausibly well. Other clients need explicit configuration.