sendmail & realtime blackholes?

Darin Perusich Darin.Perusich at
Wed Mar 13 15:42:30 EST 2002

i got the IP of there primary name server by asking the internic, whois
is such a useful tool. is run by paul vixie, the guy that wrote BIND. i'd find
it really hard to believe that he has name servers misconfigured. i'm
doing these lookups on a OpenBSD machine there is no nscd, i'm all to
familiar with nscd getting stupid. i told nslookup to use a bunch of
different name servers, uunet, adelphia.

i grabbed that rblcheck program and compiled it, it works well. i found
another blackhole, and this one worked fine so i've decided
to use it instead.


Robert Meyer wrote:
> I'm not sure about the RBL portion but I do know that if it can't look
> something up, it won't use it.  From the sound of things, something broke their
> DNS entry on the root name servers.  How did you find the IP of their DNS
> server?
> Normally, a DNS server will try to resolve a name/address locally and then
> forward it to whomever is identified as the forwarder.  If no forwarder is
> specified, it will go to the root name servers and then the root will forward
> down to the right server.  Make sure that your resolver isn't caching the
> results of the lookup.  I know that Sun workstations and servers will freqently
> have 'nscd' running which is the name server cache daemon.  If that's running,
> lookups tend to get weird on machines change their addresses.
> Hope this helps...
> Cheers!
> Bob
> --- Darin Perusich <Darin.Perusich at> wrote:
> > does anyone have experience setting up sendmail, or any other MTA for
> > that matter with the Mail Abuse Prevention System's Realtime Blackhole
> > List from it's simple enough to configure sendmail to
> > use it, just add FEATURE(dnsbl) to your before you run m4
> > against it, this i've done. i'm trying to test the feature and it
> > doesn't appear to be doing the lookup. instructions are located at
> > and it should be really
> > straight forward.
> >
> > something else that i'm finding bizarre, when i do an nslookup on
> > the lookup fails. regardless of what name
> > server i use, unless i use the name server which tells me
> > there are 3 machines serving that host. now dns by it's nature should
> > just pass my lookup along until it locates the host, if it's configured
> > correctly .
> >
> > anyone have any ideas?
> >
> > --
> > Darin Perusich
> > Unix Systems Administrator
> > Cognigen Corp.
> > darinper at
> =====
> Bob Meyer
> Knightwing Communications, Inc.
> 36 Cayuga Blvd
> Depew, NY 14043
> Phone: 716-308-8931 or 716-681-0076
> Meyer_RM at
> __________________________________________________
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Darin Perusich
Unix Systems Administrator
Cognigen Corp.
darinper at

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