BIND 9.x caching Performance under heavy loads

Bernhard Schmidt berni at
Thu Mar 31 21:37:45 UTC 2005

Kelsey Cummings wrote:

Hello Kelsey,

>>JFTR, I have a similar problem, with BIND 9.3.1 threaded running on a
>>Dual Xeon 2.8Ghz with 4GB RAM on SLES9 (Linux 2.6.5-something). The box
>>is not very much loaded (about 100-400qps depending on daytime), but has
>>to carry a big RBL which pumps up memory usage to 500M after startup and
>>has query logging enabled. It does both authorative and resolver (old
> I'd recomend moving that RBL zone into rbldnsd if at all possible and
> either targeting it with a forwarding zone or have the queriers ask it
> directly.  Bind can't hold a candle to the speed and footprint of
> rbldnsd when dealing with huge rbl zones.

I've seen that, but on this particular box it is not an option I guess.
The RBL on this machine is an non-free RBL and we are forced to strictly
limit the addresses that are allowed to query this list. Since you
cannot have "allow-query" in forward-Zones (as far as I know) and the
box is open for recursion from everywhere (old style, cleanup is going
to take a massive amount of time) it is not an option at the moment.
We're in process moving the RBL queriers to a dedicated box which could
be rbldnsd-powered (does anyone know whether
supports rsync or something similar?) with a BIND cache in front of it.

But still, the CPU hog is there, and the CPU hog is not explainable with
the general difference in speed. After all, it is running fine for some
days until CPU usage explodes. I'm running the non-threaded version now
since one day, if it keeps running this way until next week the bug is
related to threading.


More information about the bind-users mailing list