At 12:11 -0500 12/31/07, Andrew Sullivan wrote:
<apologies="sick,brief"> On Mon, Dec 31, 2007 at 11:31:55AM -0500, Edward Lewis wrote:couldn't find where it is mentioned. Synthesizing the CNAME with a TTL of 0 is a mistake because that means unaware caches (those that can't handle DNAME) will not hold onto the CNAME.Isn't that a good thing? </apologies>
I'll certainly agree that it is a toss up. Holding the CNAME will lessen repeated queries, dropping it will mean that less, um, ersatz data is held in caches.
Given that the DNAME itself can be withdrawn at any time from the authoritative zone, thus once again proving the non-temporal nature of DNS, this day I'm siding with caching the CNAME.
(This is the same issue as caching bad DNSSEC validations. Do you keep them to suppress an abuse of the system or drop them because they are false in the eyes of the would-be-holder?)
-- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Edward Lewis +1-571-434-5468 NeuStar Think glocally. Act confused. -- to unsubscribe send a message to namedroppers-request@ops.ietf.org with the word 'unsubscribe' in a single line as the message text body. archive: <http://ops.ietf.org/lists/namedroppers/>