Recursive bind becomes unresponsive with high load

Michael Brunnbauer brunni at
Fri Apr 1 16:29:32 UTC 2016

Hello Mathew,

On Fri, Apr 01, 2016 at 04:01:04PM +0000, Mathew Ian Eis wrote:
> What OS are you running your BIND server on? Is it virtualized?

Linux Kernel 3.4.111 with glibc 2.22, 32bit, not virtualized. No distribution -
everything was compiled by hand.

> Is it fully unresponsive, or could it be simply taking longer to respond than your client timeout?

Assuming that bind would report dropped queries, I guess it is the latter.

Regarding the suggestion made by Tony Finch about too many TCP connections
in the TIME_WAIT status: That would have been a good explanation. But I do not
see more than 200 TCP connections in TIME_WAIT status when the problem occurs
and not more than 5000 TCP/UDP connections with port 53. 


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