Multiple A Records - Followup Question

David Ford david at blue-labs.org
Sun Oct 2 20:42:39 UTC 2016


On 2016-10-02 12:59, Reindl Harald wrote:
>
>> IOW, can a given *IP* appear in more than one A record? I realize
>> that this does have the problem that the reverses would resolve to
>> hostX not
>> test
>
> on IP should only have on PTR - period
>
> avoid anything else than PTR/A-matching if the machine is supposed to
> send outbound mail

it is very helpful to have multiple PTR records for an IP on a mail
server so anti-spam engines can accurately make fully verified forward
and reverse lookups not just for DNS but also certificate verification.

mail servers that can't correctly emit the right EHLO for outbound email
should remain in the 1990s.



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