On Tue, Apr 29, 2025 at 09:07:04AM +0200, Endre Szabo <endre.szabo@ripeatlas-ml-nerudrr.rediremail.com> wrote a message of 13 lines which said:
How can I determine which DNS server it is using to provide a NOERROR? You can query o-o.myaddr.l.google.com. for TXT records or myip.opendns.com <http://myip.opendns.com/>
Or resolver.00f.net or _country.pool.ntp.org or whoami.v4.powerdns.org or whoami.fastly.net or whoami.akamai.net or resolver-identity.cloudfront.net or whoami.ultradns.net. It is apparently a Google resolver: % blaeu-resolve --nsid --probes 1006193 --type TXT ip.dyn.bortzmeyer.fr ["172.217.32.208" NSID: None;] : 1 occurrences Test #100371567 done at 2025-04-29T07:36:26Z This IP address is a Google one. Apparently, the resolver used by this probe, 10.5.21.3, is not Google - it has no NSID - but forwards to Google, may be after applying a local blacklist. Another test showed the address 2620:171:75:f003:9999::244, which belongs to PCH, so may be 10.5.21.3 is load balancing between gpdns and quad9.