Re firewalls: I've been forced to adjust firewall rules to be stateless to get busy DNS servers to work. If the state table is filling, that's easy to check. Stateless rules have traps for the unwary so assure yourself that you understand all the issues. Specifically, make sure return traffic isn't triggering state.
Over the years as typical memory in a server grows, systems' default tuning parameters have increased and often things do just work without such adjustments. Another tuning issue for bind is assuring it is configured to handle sufficient recursive queries for your load. This is also easy to check so should be one of the first things checked. Given that you say only one of your servers' IP addresses has the issue, all this seems moot. Viewing the connections with netstat seems useful. Or if there is another system on the same IP, it is crucial to fix that. Such a problem could just kill communications but it could also cause symptoms that only show under load. Another thought is a firewall in front of your server. And speaking of firewalls, some have a feature to govern the level of load they allow into of a part. John Wobus Cornell University IT _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users