ns1-proddns.glbdns.o365filtering.com unreachable?

Wed Jul 6 09:49:23 UTC 2022

On Wed, Jul 06, 2022 at 11:37:40AM +0200,
 Bjoern Franke via NANOG <nanog at nanog.org> wrote 
 a message of 10 lines which said:

> <tenant>.mail.protection.outlook.com seems to throw servfails.

The authoritative name servers for this domain do not handle EDNS
(which was specified only 23 years ago) so the resolvers that do not
fallback on EDNS (probably the majority) return a SERVFAIL.

Seen with RIPE Atlas probes:

% blaeu-resolve -r 500 --type NS mail.protection.outlook.com
[ns1-proddns.glbdns.o365filtering.com. ns2-proddns.glbdns.o365filtering.com.] : 319 occurrences 
[ERROR: SERVFAIL] : 138 occurrences 
[] : 1 occurrences 
Test #42222155 done at 2022-07-06T09:24:50Z