In message
<6(_dot_)2(_dot_)5(_dot_)6(_dot_)2(_dot_)20130504095840(_dot_)0d4a98d8(_at_)resistor(_dot_)net>,
S Moonesamy writes:
Hi Doug,
At 16:19 03-05-2013, Doug Barton wrote:
I am not saying that the WG members (or chairs) should be given the
wet-noodle treatment over having reached a bad decision, but what is
cross-area review for if not to catch cases where the WG echo
chamber/tunnel vision/what have you -- resulted in a bad outcome?
I'll try explain the problem as I saw it.
(a) You should have both X and Y
(b) You must have either X or Y
(c) If you have X and Y they must be identical
(d) I can ask you for either X or Y, or for both X and Y
Regards,
S. Moonesamy
The DNS does not guarentee that the result of 2 consecutive
queries for the same data will be the same even to the same
server (cache or authoritative).
RFC 4408 says that *data* MUST be the same if both records are
present in the zone. It the operator breaks that MUST then you get
inconsistent results. Note this is no different to changing the
contents of the record. You will get inconsistent result while the
record are in transition.
For the client side you assume the MUST is being honoured as there
is no way (other than to ask a * query directly to the authoritative
servers) to check that this is so. You take the first result which
returns *data* and use it.
This was never a real problem. Not all MUSTs need to be checked.
Note DNSSEC also has MUSTs about what the server side need to do
which the client side cannot check. This is the nature of DNS.
Mark
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka(_at_)isc(_dot_)org