On 08/30/03 at 19:25 -0600, LuKreme opined:
> On Aug 30, 2003, at 12:31 PM, Global Homes Webmaster wrote:
> > On 08/30/03 at 01:35 -0400, chris opined:
> >> I'll have to try the cn-kr next and see how much more it stops.
> >
> > By itself, probably quite a bit. But there's a significant overlap
> > with CBL and other lists with other purposes (easynet, OPM, etc. --
> > the reason so much spam gets relayed through Chinese hosts is that
> > so many of them are open proxies and/or open relays, and the
> > Chinese don't seem to care about closing them). If you're already
> > using one or more of those lists, you might not see as big a drop
> > as you might expect.
>
> exactly, as I said, 90% of the blocked pam gets hit by cbl, and 9.5%
> gets hit by cn-kr.
>
> If I reversed the entries, cn-k would catch about 40%, but that would
> increase the overall number of DNS requests I'm using, so I list cbl
> first.
Mmm... I'm not sure that's how it works. The order RBL servers are listed
does make a difference in terms of which one is used as the basis of
rejecting a connection, so you get the statistical effect you've described.
But I don't think SIMS does fewer DNS look-ups. It seems to me that it
would be incredibly inefficient if SIMS waited for a response to each
look-up before it sent the next one. For one thing, you could probably
expect a non-trivial number of SMTP connections to time out waiting for RBL
look-ups to complete if they were done sequentially rather than
concurrently. And you'd expect connections from hosts that are not listed
in any RBL to time out more often, since they'd have to wait for every RBL
to be queried in turn. I don't know for sure how SIMS does RBL look-ups,
but I'd be surprised if they're performed sequentially, waiting for each
one to complete before sending the next.
--
Christopher Bort | [EMAIL PROTECTED]
Webmaster, Global Homes | [EMAIL PROTECTED]
<http://www.globalhomes.com/>
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