From: Chris Bongaarts (
Date: 2004-10-29 06:40:44

As Marko M?kel? once put it so eloquently:

> There's no need to do reverse DNS lookup.  It wouldn't work for any web hotel
> hosted domains (like many small businesses), or domains run behind a
> DSL connection (like yours).  I wonder why a few years back some sites
> insisted on a successful reverse DNS lookup before allowing connections.

Just a sanity check on the competency of the network administrators.

> Didn't WHOIS work for IP addresses back then?

The AUP did not allow automated use...

FWIW, at work (a large university) we block sites that do not have
working reverse DNS AND forward DNS mapping back to the original IP,
except for a (large) number of "grandfathered" addresses that we know
about.  It blocks a LOT of spam, and the false postives are shrinking
over time.  

There are other larger organizations/ISPs, including AOL,
who are also doing this sort of blocking, which makes it easier to
tell sites to clean up their act.  (Their current list of blocking
rules is at .)

Now, just to get back on topic:  if you hooked a C64 to the net and
ran a mail server on it, could you implement these sort of checks? :)
 Chris Bongaarts

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