[SAGE] How to retire a DNSBL without sacrificing a domain?

["Derek J. Balling" <dredd@megacity.org>]

Once upon a time, when I was really upset with Yahoo's complete lack  
of a functioning abuse department, I created the "YBL", containing  
all the Yahoo IP addresses I could find. I was silly, and put it in  
'ybl.megacity.org'. Right now, I'm pointing ybl.megacity.org at  
$HOST, which is not one of my main servers, and it happily serves up  
the data.

I decided today to retire that zone. I never really advertised it  
much of anywhere except for a couple usenet posts, so I wouldn't  
really call it an "advertised and supported service" of any sort. I  
pointed the NS set for it, with a ludicrously high TTL, to  
"localhost.megacity.org" (which points to 127.0.0.1).

Now, in theory, those folks should query me, get the NS set with a  
huge TTL, and never ever come bother me again for a DNSBL lookup.  
Except they do, and in fact, they do even more lookups (my cricket  
graphs showed my traffic increased by like 1000% in the process).  
Apparently, they query me, get the NS, query themselves, fail, and  
then query me AGAIN, over and over again.

What's the best practice on this? How the hell do you make those  
sorts of services go away? Near as I can tell, whatever the NS set is  
for megacity.org is going to get hammered with these forever and  
ever, and if I try to negatively-reinforce people from using it, it  
just crushes my link even worse. :-(

Thoughts?

D