Re:Packets per Second Limitations in EC2
by john37386 on Saturday October 27, 2018 @08:41AM
(#18315472)
Yep I mistaken Security groups with Network Acl. Thanks. It's in the best practices to not track dns for big systems.
From powerdns https://doc.powerdns.com/recursor/performance.html
As suggested, it's very likely they hit the connection tracking limitation: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-ne...
I've personally witnessed teams hit this specifically for DNS (usually for internal, where you have explicitly permitted src/dst).