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Re: current usage of AAAA implicit MX?

2008-04-04 13:48:43

On Fri, 4 Apr 2008, Arnt Gulbrandsen wrote:

Michael Storz writes:
- number of MTAs from which we accepted emails over IPv6: 255

Perhaps you could take the email addresses sent to you by those MTAs and
see how many have MX records, how many only A and how many only AAAA?


Ok, I've done that. It took some time and I don't know if it is helpful.

From the 255 MTAs, I got emails with 504 different domains in 'mail from'
(I excluded the outgoing servers of the german ISP, because it
would distort the statistik).

160 domains have a path back over IPv6, 155 via MX RRs and 5 via A/AAAA
RRs only:

ok: -A-> -PTR->
no:                               -PTR-> -A->
ok:            -AAAA-> 2001:738:5001:0:0:0:0:90 -PTR->
no:                                             -PTR-> -AAAA-> 

no: -A-> -PTR-> Balder-227.Proper.COM -A->
no:              -AAAA-> 2001:470:1F04:392:0:0:0:2 -PTR-> -AAAA-> NXDOMAIN

ok: -A-> -PTR->
ok:                   -AAAA-> 2001:718:2:2600:0:0:0:3 -PTR->

no: -A-> -PTR-> -A->
no:                   -AAAA-> 2001:600:1003:1:0:0:0:73 -PTR-> 
-AAAA-> 2001:600:1003:1:0:0:0:73

ok: -A-> -PTR->
ok:               -AAAA-> 2001:878:100:12:0:0:0:137 -PTR->

3 of them are the email servers of their domain without host subdomain:

% dig +short mx
% dig +short mx
% dig +short AAAA
% dig +short mx
% dig +short AAAA

From the 155 MX RRs

- 58 MX RRs, where all hosts have A + AAAA RRs
- 44 MX RRs, which point to one host which has A + AAAA RRs
- 43 MX RRs, where at least one of the backup MX has only A RRs, all
  others with A and AAAA RRs
- 5 MX RRs, where the primary has only A RRs, but backup has A and AAAA
- 5 MX RRs with mixed hosts, same prio but some have only A RRs other both
- 0 MX where one of the hosts has only an AAAA RR, which means
  prioritizing a protocol is not used


- 3 of the MX point to themselves, which means the domains are hosts with

Michael Storz