D'oh! I sent this before seeing the thread on RBL look-up order. Ignore my
ramblings. [Although, I'd still like to see a definitive description of how
SIMS does RBL look-ups from someone who actually knows what the code does.
Dmitry popped his head up a few days ago, maybe he still monitors the
list?]
On 08/31/03 at 16:15 -0700, Global Homes Webmaster opined:
> 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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