Thanks Jesse & Tim for your help. I cleaned up my IP tables a bit and replaced unbound with Bind9 configured to use a high-speed regional open DNS resolver and things seem to be much better. Total server throughput for the 2 relays is back up to around 190 Mbps (and climbing) with no more warnings in the logs. Not sure what happened last week that started the problem, but at least it seems to be better. Thanks again!
-Pat
On Jan 29, 2016, at 8:46 AM, Jesse V kernelcorn@riseup.net wrote:
Wild guess, but I'd suspect a routing issue. You'd get duplicate responses if the requests are being sent twice. Have you recently made any changes to iptables or your kernel routing table? Do you get double responses if you ping another server, say example.com?