At 13:34 7/08/02 -0700, Chris Wedgwood wrote:
On Sun, Aug 04, 2002 at 11:33:32PM +1200, Peter Mott wrote:
But the telecom delegated /23 had no name resolution.
Empty/broken zone, lame delegation or name-servers not responding?
For your original email is sounds very much like the latter, in which case *most* things will keep working albeit a little more slowly at times perhaps.
Email won't be lost, it will remain in the queues, web-traffic should be blisfully ignorant of this. [snip]
Sorry, I just don't understand why this was such a problem... reverse is broken for so many people and they never notice it.
It depends *whose* reverse dns is broken.... MTA - MTA transfer of mail will normally get around the problem of broken reverse DNS, usually just with a bit of delay in the delivery of the message, and perhaps a lookup failure warning in the headers. This is because MTA's usually have connection timeouts that are longer than dns lookup failure timeouts. However if the reverse DNS for end users (eg, dialup, Jetstream, and so forth) is broken in such a way that the DNS times out instead of immediately failing, this can pretty much kill email for those end users. When the user connects to the mail server, most MTA's (Sendmail certainly does) try to do a reverse lookup on the clients address. If that failed immediately then there wouldn't be a big problem, but if the nature of the dns failure means that every single lookup has to time out, (typically a couple of minutes) then the mailserver wont respond with its welcome banner until after that timeout. Trouble is, most typical end user email software simply won't wait that long before giving up, and even if it would, the user themselves usually get impatient and cancel the attempt.
From the point of view of that end user their email isn't working...
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