[Dnsmasq-discuss] strange list server bounces

Simon Kelley simon at thekelleys.org.uk
Tue May 8 21:17:34 BST 2012

On 08/05/12 20:58, starlight at binnacle.cx wrote:
> Another way to fix this if a sub-domain for
> the list server is aesthetically (or practically)
> more desirable, is to replace the CNAME record
> with explicit A and AAAA records.

The existence of the sub-domain for the list server is a fact on the 
ground: I can't easily change that now even if I wanted to.

Agreed that explicit A and AAAA records would be better, except that the 
A record is actually dynamic: it could (in theory) change at any time if 
my ISPs DHCP server were to give me a new lease for a different address. 
That's handled for thekelleys.org.uk by dyndns.org, but I don't want to 
have the complication of keeping multiple A records up-to-date: I'm not 
sure dyndns even supports that. The AAAA record is a real static address 
(provided by a tunnel broker) but that doesn't help whilst the A record 
problem remains.

> The presence of CNAME historically is stronger
> than permission to rewrite, rather it demands
> rewriting of the address.  This makes logical
> sense as CNAME is primarily intended for migrating
> from one DNS name to another--not so much
> as an alias mechanism.  However newer MTAs
> apparently fail to comply properly so the
> rewrite is not always happening as it should.

Given how long this has taken to come to light, I suspect that most 
don't. The MTA and mailman installation was new a few months back, the 
previous one may have accepted list mail to thekelleys.org.uk, I don't 
remember. At the very least it has been in this state for months and 
possibly for years.

Anyway, thanks for the education. I've learned something new and it's 
fixed now.



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