DNS performance monitoring
Does anybody actually monitored their setups' DNS servers performance?
When large number of hostnames that need to be resolved are inbound (lets say 300 threads on verification only), somwhere along the line SER freezes for 0.5 to 7 seconds, averaging around 3. During that time SER won't respond, if I have dnscache enabled I would see some DNS-related stuff so its definitely DNS thingy. I've tried to hook up Google DNS, same story. I've also tried to find some DNS-related tools but no one fits the role.
Are you guys able to verify URLs at 200+ threads without hiccups on ISP or Public DNS? Any tools that you know that would help to monitor situation somehow? Any ideas are welcome. 