Explicit priority MX with only AAAA record

Steve Bertrand steve at ibctech.ca
Wed Jun 25 15:59:59 CEST 2008

Marcus Stoegbauer wrote:
> Hi,

>> I've been considering breaking that, and having separate explicit MX 
>> records for each an A and an AAAA record, and setting the IPv6 MX as 
>> priority, the v4 as next priority.
> We had this setup for about 1.5 years for our (really small) company 
> domain and I didn't receive any complaints during this time that mails 
> couldn't be delivered or got lost.
> However there are said to be mail daemons which don't behave well when 
> the first MX can't be resolved to an A record and stop delivering the 
> mail altogether.

Thats exactly what I am afraid of happening.

> I don't see the upside on changing from "AAAA/A" to "first AAAA, then 
> A". In my eyes your current setup is the best and easiest solution 
> because it should give you exactly the same behaviour, no matter which 
> IP protocol you're using.

I had been thinking that. Any implementation I've run into so far will 
always prefer IPv6 if it is enabled, so I'll take your advice and leave 
well-enough alone.



More information about the ipv6-ops mailing list