On Sun, 2005-07-03 at 21:40 +0000, John Levine wrote:
The question is really whether a change to this RR may cause a
second RR to appear for some period of time in a local cache. The
TTL in the cache would be independent of the new RR just published
where there could be some overlap.
What Tony said. Any DNS implementation that does that is broken.
Like I said, if you read the various DNS RFCs, that is a situation
they specifically considered and disallowed.
RFC1035:
,---
| 7.4. Using the cache
| ...
|
| In a similar vein, when a resolver has a set of RRs for some name in a
| response, and wants to cache the RRs, it should check its cache for
| already existing RRs. Depending on the circumstances, either the data
| in the response or the cache is preferred, but the two should never be
| combined. If the data in the response is from authoritative data in the
| answer section, it is always preferred.
'---
Well it does say should, and if all resolvers adhere to this, then this
_should_ not cause a problem...
-Doug