DNS question, null MX records

Mark Andrews marka at isc.org
Wed Dec 16 14:20:41 CST 2009


In message <167CAB40-71D7-4BF9-988A-1A188B433C37 at hopcount.ca>, Joe Abley writes
:
> 
> On 2009-12-15, at 19:09, Tony Finch wrote:
> 
> > On Tue, 15 Dec 2009, Florian Weimer wrote:
> >> * Eric J. Esslinger:
> >>=20
> >>> I found a reference to a null MX proposal, constructed so:
> >>> example.com    IN    MX 0 .
> >>=20
> >> I think this is quite controversal.
> >=20
> > My impression from discussions on various IETF lists is that most =
> people
> > think it is a good idea, it is already reasonably widely implemented, =
> but
> > no-one has the time and persistence to push a spec through to =
> publication.
> 
> When I attempted to document a similar idea (using an empty label in the =
> MNAME field of an SOA record in order to avoid unwanted DNS UPDATE =
> traffic) the consensus of the room was that the idea was both =
> controversial and bad :-)
> 
> http://tools.ietf.org/html/draft-jabley-dnsop-missing-mname-00

Well UPDATE traffic is supposed to go to the nameservers listed in
the NS RRset prefering the MNAME if and only if the MNAME is a
nameserver.  Lots of update clients don't do it quite right but
there are some that actually send to all the nameservers.

Setting the MNAME to "." does not actually address the problem.

Mark

> Joe
> 
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org




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