[Mimedefang] DNS and MX records

Jan Pieter Cornet johnpc at xs4all.nl
Thu May 11 03:23:38 EDT 2006


On Wed, May 10, 2006 at 08:55:15PM -0400, David F. Skoll wrote:
> > For example: during the registration process IDNL (the Dutch .nl
> > registry) will check for valid MX's; if these don't exist an error
> > message is generated.

The idea is to disable mail from/to certain subdomains, eg, you
publish:

www	IN MX 0 _not_valid_for_email

causing www.yourdomain.tld. to be invalid for email.

> Why?  I am unaware of any RFCs that require a domain to accept e-mail.

The dutch domain registrar uses a rather strict and sometimes
illogical set of rules. Some of the rules are written here:
http://www.sidn.nl/ace.php/c,728,2892,,,,Annex_1_Technical_Requirements.html

But there are also some unwritten rules. For example, any
"secondary" NS cannot have a higher serial in the SOA record as
the "primary" NS. This is a really odd requirement in case you
don't distinguish, internally, between primary and secondary
nameservers (all our nameservers are "primary", in a way, and are
fed by a common database backend).

I seem to recall there's also a requirement that one of the
registered contacts (I believe admin-c) has to point to an
email address at the domain itself, but I cannot easily find it.
This would explain why the domain needs to have MX records (or
an A record).
 
> Does the Dutch registry periodically recheck?  Because it would
> be pretty easy to throw out the MX records once the domain has been
> registered.

They don't recheck as far as I know.

-- 
Jan-Pieter Cornet <johnpc at xs4all.nl>
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