SV: Bind bind high recv-q

Søren Andersen SOAN at
Sun Dec 6 20:32:25 UTC 2015

Hello Cathy,

I tried to set prefetch 0; 

I notice my server got more loaded but I still have periods of  3-5 seconds where there are packets in the revc-q. - Do you have anything else in mind I can try?


-----Oprindelig meddelelse-----
Fra: bind-users-bounces at [mailto:bind-users-bounces at] På vegne af Cathy Almond
Sendt: 4. december 2015 23:13
Til: bind-users at
Emne: Re: Bind bind high recv-q

On 04/12/2015 12:34, Tony Finch wrote:
> Søren Andersen <SOAN at> wrote:
>> I'm experiencing some strange problems with my bind installation. - I 
>> notice my bind recv-q is quite high sometimes.. therefore my DNS 
>> clients can experience DNS lookup to take 1-4 secs. My bind is 
>> running on a 4 core vm I VMware with 8Gb ram. - At peak I receive 
>> app. 700-800 QPS. - The load is 20-40% on each CPU core. - I've also configured 2 RPZ zones.
> Is your server an open resolver being used as part of a DDoS attack?
> Do you have compromised client machines running malware that hammers 
> your server?
> Find out where the queries are coming from using netflow or tcpdump or 
> query logging.
> Tony.

Also, if your server is not well-connected (if you have slow or intermittent packet drops) between your server and the Internet, then you might be affected by a defect in the prefetch implementation that can impact performance for some server environments.

See and see if disabling prefetch helps in your environment.

(The problem that this article talks about will be fixed in 9.10.4).

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