bind forward to rbldns server intermittently fails

[Mark Andrews]

> Hi
> I am using bind 9.2.4 on Centos 4.2 
> We run a fairly  high traffic Antispam service with 6-7 million mails
> hitting a day ( 14 load balanced servers each serving upto 35k
> mails/hour ) 
> 
> For checking antispam , we use a "local" rbldns server running rbldns on
> port 530 and every scan server is configured to forward all rbl-zones to
> the rbldns server
> 
> so in my named.conf I have 
> zone "xbl.spamhaus.org" IN {
>  type forward;
>  forward first;

	forward only;

>  forwarders {
>  192.168.2.2 port 530;
>  };
> };
> 
> The hits on the rbldns server would be around 1000qps 
> 
> Everything seems to work perfectly fine .. but sometimes all of sudden
> the named server seems to have failed When I "dig" for a listed ip I get
> a negative response. I restart bind and then for the same ip I get
> positive response
> 
> Any ideas how do I debug this 
> 
> Thanks
> Ram
> 
> 
> 
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org