Re: houston.rr.com MX fubar?

[Mark Andrews <Mark_Andrews () isc org>]

In article <bb0e440a0801141838r736462dey64094e555cd6d0a6 () mail gmail com> you write:
> On Jan 14, 2008 5:08 PM, Tony Finch <dot () dotat at> wrote:
>
> > the "." convention then it will look up the root's AAAA and A records,
> > which is stupid but should cause the message to bounce as desired. However
> > if it does implement the convention (just like the "usage rules" for a SRV
> > record target of "." in RFC 2782) then it can skip the address lookups and
> > save the root some work. (It can also produce a better error message.)
> > This really ought to be explained in draft-delany-nullmx.
>
> The draft died.  And I think this stuff about looking up A / AAAA for
> the root was certainly raised in the IETF sometime back.  Not that
> there isnt enough junk traffic (and DDoS etc) coming the roots' way
> that this kind of single lookup would get lost in the general noise ..
>
> Might want to revive it and take it forward?  I rather liked that
> draft (and Mark Delany cites me in the acknowledgements as I suggested
> a few wording changes for the definition of a null MX - dot terminated
> null string, STD13 etc, during his drafting of the document)
>
> --srs
>
> -- 
> Suresh Ramasubramanian (ops.lists () gmail com)

        There are lots of places in the DNS where "." makes sense
        as a null indicator.  RP uses it today, as does SRV.  MX
        should use it and fallback to A should be removed.  It
        actually takes more cache space to record that a MX record
        does not exist than it takes to record that a A or AAAA
        record exists (SOA rdata is atleast 22 octets).

        draft-ietf-dnsop-default-local-zones used it for SOA RNAME
        but was changed under WG pressure.

        A and AAAA should use 0.0.0.0 and :: to indicate that a host
        exists but is not currently connected.

        Mark