SV: Bind bind high recv-q
SOAN at stofa.dk
Sun Dec 6 20:32:25 UTC 2015
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?
Fra: bind-users-bounces at lists.isc.org [mailto:bind-users-bounces at lists.isc.org] På vegne af Cathy Almond
Sendt: 4. december 2015 23:13
Til: bind-users at lists.isc.org
Emne: Re: Bind bind high recv-q
On 04/12/2015 12:34, Tony Finch wrote:
> Søren Andersen <SOAN at stofa.dk> 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.
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 https://kb.isc.org/article/AA-01315 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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