Named / cache

[Vu Pham]

I have a cache-only dns server that has been running for a long time ( 450
days and 19:57) . It uses named on Linux. And it works fine until recently I
got some notice about slow access to the web sites when users first enter
the sites.

Running "top" on that server shows named took 67% memory and the load
average was 1.50. After stopping/starting named, everything works fine.

So, does named keeps the cache forever and never clear the old entries ? 

Thanks,

Vu