I ran into a few errors during load testing on my bind server the other day and found ways to quickly fix them. Your mileage may vary but for me these helped. Note these are just the configuration names with no settings ! I did this so you can evaluate whats best for your system!
I will make this my default post for these errors and the config changes I did to fix them:
ISSUE: named: dispatch 0x7fb0180cd990: open_socket(0.0.0.0#8611) -> permission denied: continuing
FIX: raise the range of ports in `use-v4-udp-ports` make sure that range does not overlap with existing UDP services.
ISSUE: named: clients-per-query increased to 20 (or other number)
FIX: Raise `max-clients-per-query` and `clients-per-query` a “0” will set to unlimited. Be careful of this due to resource exhaustion!
ISSUE:DNS queries timeout/lost under load (dnsperf or other tool can show this).
FIX: (OS) set “net.core.rmem_max” and “net.core.rmem_default”