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