On 04/04/2012 08:48 PM, Bob Hoffman wrote: > No idea where else to ask this and get a real qualified answer but here. > Not exactly pure centos question....but... > > I am adding blacklists to my postfix smtpd settings. > I have the inkling that after the first lookup for a domain or ip that > my dns caches the result and I no longer bother the RBL or RHSBL list > owners anymore in that instance. > > Is that correct? I hate to waste their resources if it is not. > > thanks, > bob > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos Not exactly. It is whatever TTL they return, though generally short for two reasons, they and you probably want it so that they can quickly remove entries from the blacklist once issues have been resolved. They want to know how often you query the blacklist, because they want to charge a fee if you are a large site with high volume queries. I guess they need to fund their service somehow. Nataraj