[dns-operations] ns1-proddns.glbdns.o365filtering.com unreachable?

[Daniel Baumann]

Hi,

> Anyone else with trouble to reach the *.o365filtering.com DNS Servers?

yes.

this started ~mid last week only sporadically (one fail every ~12 to 24h).

since today, we cannot resolve
${tenant}-mail-onmicrosoft-com.mail.protection.outlook.com. anymore (for
which ns1-proddns.glbdns.o365filtering.com and
ns2-proddns.glbdns.o365filtering.com are authoritative).

we tried locations in Switzerland and Germany with the same result.
8.8.8.8 fails the exact same way too.

1.1.1.1 seems to be able to resolv them, so for the time being we're
stub-resolving mail.protection.outlook.com to 1.1.1.1 in order to be
able to send mails out.

also: ns{1,2}-proddns.glbdns.o365filtering.com resolv to the same IP, do
not support EDNS and don't answer on TCP queries.

Regards,
Daniel