> I still think that the majority of DNS requests will be > answered by the local (caching) DNS server. Besides, DNS > requests going out on the NIC are more expensive then those > going on the loopback interface.
This is probably true in a vacuum, but I think if you're going to compare the two, you also need to factor process context switches and hindrance to other parts of the system. Running a local caching server means that the server is likely being used by the system for other things too, and this means frequent interruptions to your mail services, or if your mail services are CPU hogging, other DNS lookups on the same server wait until your mail services complete their full process quantum. It's all a balance, and sometimes running something locally can be a hindrance vs. running a dedicated remote service. Consider that you can allocate LOTS of RAM to a dedicated DNS server, where you probably would not desire having a local DNS service compete for resources used for mail services. The NIC will also DMA process and handle incoming/outgoing packets while the system is doing other mail processing, so there's some overlap. But you're right, YMMV and benchmarks are the only way to be sure. ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ AMaViS-user mailing list AMaViS-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/amavis-user AMaViS-FAQ:http://www.amavis.org/amavis-faq.php3 AMaViS-HowTos:http://www.amavis.org/howto/
