Re: what is up with the PG mailing lists?

On Thu, Nov 01, 2007 at 03:23:12PM -0400, Tom Lane wrote:
> Well, the current problems seem to be entirely inside hub.org, and so
> all this banter about DNS etc seems not relevant.  A handy example is

Could be.  The main point is to get examples of the sort you just
provided -- if we can get a nice collection, then it becomes
reasonably likely we'll track the issue.

That said, I'm not suggesting that DNS _is_ the problem, merely that
it could be.  Of course, if Marc is using the same DNS for internal
and external DNS queries, and the externals are under attack, then
his internal DNS is hosed.

Or if there's a reverse tree somewhere in the path that isn't working
100% of the time, and the mail servers are all trying to do reverse
lookups.  (This is a remarkably common source of breakage, I have
learned as a result of my work on a current internet draft.)

Mail gremlins are notorious for their difficulty in debugging partly
because of all the horrible interaction with DNS.  Add a couple
different name servers, 3 MX records, and the occasional bad reverse
path, and you're into serious pain, especially after your spam filter
proceeds to do much of it all over again.  Even a single hop can be
expensive then.  But I do think there's something going on in the
suspicious hop, and only Marc can diagnose it.

A

-- 
Andrew Sullivan  | ajs@crankycanuck.ca
"The year's penultimate month" is not in truth a good way of saying
November.    --H.W. Fowler