On 11/23/2017 02:23 AM, Jared Mauch wrote:
I also created this measurement, which is a ping one to measure latency to identify what countries receive a poor response. https://atlas.ripe.net/measurements/10291137/#!probes
All those measurements will only show part of the story though: Quad9 seem to do some _extremely_ weird nonsense. We were measuring ICMP-latency just from different machines on the same subnet and saw _huge_ differences in the responses:
rtt min/avg/max/mdev = 15.088/15.202/15.366/0.155 ms rtt min/avg/max/mdev = 4.066/4.134/4.265/0.106 ms
Those times are reproducible, a machine will always get the same 15 or 10 or 4 ms ping. So their anycasted 9.9.9.9 seems to internally redirect queries based on source-IP-hash, and if you're unlucky, they redirect you to a server at the other end of the continent, that has a latency that is worse than if you used a DNS in another european country. What this means for your measurement is that if your probes IP changed it might suddenly get a response time that is worse by a factor, even if it was still on the exact same network. -- Michael Meier, Zentrale Systeme Friedrich-Alexander-Universitaet Erlangen-Nuernberg Regionales Rechenzentrum Erlangen Martensstrasse 1, 91058 Erlangen, Germany Tel.: +49 9131 85-28973, Fax: +49 9131 302941 michael.meier@fau.de www.rrze.fau.de