Re: Bogus nic.fr behavior

["Eric A. Hall" <ehall@ehsco.com>]

> That's probably technically slightly too much (TCP support is just
> a SHOULD I think), but in practice it is a good thing to check

TCP is required for MX lists which are truncated.

RFC 1123, section 6.1.3.2:

  A mailer must not use a truncated MX response, since this could
  lead to mail loops.

TCP is not required if you can restrict the number and size of MX entries
for a domain name beforehand. Otherwise nobody will be able to send mail
to the affected domain names, which will invalidate the zone.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/