> On Dec 6, 2016, at 1:44 PM, MRob <mro...@insiberia.net> wrote:
>
> Last few days, I'm seeing large amount of failures in a log file for domains
> using protection.outlook.com:
>
> to=<u...@example.com>, relay=none, delay=13190, delays=13187/0.08/2.2/0,
> dsn=4.4.3, status=deferred (Host or domain name not found. Name service error
> for name=example-com.mail.protection.outlook.com type=AAAA: Host not found,
> try again)
Some of the MX hosts behind *.mail.protection.outlook.com have AAAA
records, and there is not generally a problem resolving these:
nist-gov.mail.protection.outlook.com. 10 IN AAAA 2a01:111:f400:7c0c::11
nist-gov.mail.protection.outlook.com. 10 IN AAAA 2a01:111:f400:7c09::11
nist-gov.mail.protection.outlook.com. 10 IN AAAA 2a01:111:f400:7c10::10
The nameservers for this zone don't support EDNS0, and there've been
recent reports of some resolvers not handling FORMERR correctly
(alpha versions of PowerDNS recursor on Debian/Ubuntu systems IIRC).
Make sure your resolver handles EDNS0 rejection correctly.
--
Viktor.
