Re: provisioning software, was DNS RRTYPEs, the difficulty with

In message <4F564AC2(_dot_)1040502(_at_)tana(_dot_)it>, Alessandro Vesely 
writes:
> On 06/Mar/12 16:00, John R. Levine wrote:
> > > > We seem to believe that the "D" part is deployed so that adding new
> > > > "unknown" RRTypes is not an issue.
> > > I think this is correct, but OTOH someone recently asked about 
> > > possible issues in this area, and if I remember correctly,
> > > received no response.
> > Last month I ran into a guy on the dmarc list who complained that his
> > server returns NOTIMP in response to queries for SPF records ("because
> > it doesn't implement them") and clients were doing odd things.  But
> > it's been a long time since I've run into anyone else like that, so I
> > agree, it's not an issue.
> Hm... I have no idea how such response gets cached.  RFC 2136 says
> that "an appropriate error will be returned to the requestor's caller"
> when RCODE is SERVFAIL or NOTIMP.
>
> Is that the same case that Scott noticed when he wrote:
>
>    Particularly when querying for SPF records of type SPF, persistent
>    2 ServFail results are /not rare/.
>
>    http://www.ietf.org/mail-archive/web/spfbis/current/msg00259.html
>    (emphasis added)
> ?
>
> IIRC there was also a mirroring issue...
>
> At least, I think these issues will gradually vanish as the software
> at the relevant servers gets upgraded.
A RFC 1035 recursive server should be able to handle SPF.  It's
just a opaque data blob to it with a name, type, class and ttl
attributes.  To serve SPF a RFC 1035 needed to be upgraded as it had
no way to store / load the record.

DNS software developers should read Section 3.6. "Defining new types,
classes, and special namespaces", especially the sentence:

                New definitions should be expected.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka(_at_)isc(_dot_)org
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