Multiple A records and reverse DNS

[Thomas Schulz]

> Am 17.03.2016 um 14:53 schrieb Thomas Schulz:
>> This is not a BIND question but I hope people here will know the answer
>> We are switching service providers and I understand that many email
>> SPAM prevention systems insist on the reverse DNS matching the forward
>> DNS. If I have two A records for our mail server and the reverse record
>> matches one of them, will that be good enough. Or will the fact that
>> the other A record does not match cause trouble
> 
> when you have two A-recods then you have two IP's
> each of them should have a PTR with *only* the name of the A-record
> and in a good setup "smtp_helo_name" matchs too

Thanks to everyone for their answers. In switching service providers we
have arranged for both providers to be active at the same time for a few
weeks. The old provider has reverse DNS set up but the new provider does
not yet have that set up. I was thinking of allowing incomming email from
both by having two A records but alowing outgoing email only through the
old provider that has the working reverse DNS. When the new provider also
has reverse DNS set up then I can switch outgoing email and close down the
old connection.

I turns out that it is harder than I thought to allow incomming
connections from both providers at the same time, so I may not do
that after all.

Tom Schulz
Applied Dynamics Intl.
schulz at adi.com