Hello
I use a routerboard as my core router, service 300 clients, cpu is at about 50%
After a few days or even weeks dns stops working, I can no longer resolve domian names.
I reduces the cache size and this seems to make it last longer (but in may be a fluke)
Has anyone else seen this?
2.9.43 rb500@400mhz
Never seen that, but watch your available RAM. When it gets too low, things get weird fast.
Thanks (again) 
Ram free is 40MB but I will look when it fails next.
If I have no resolution I’ll just move DNS cache to my proxy or something & setup secondary on the clients.
You could look at just redirecting the DNS requests to OpenDNS.
Did you wrote a mail to the support? How big your DNS table is? MIght it be DNS server issue?
Hello
I did redirect to another dns with dst-nat this was fine but did not work for other dns server I redirected that wanted to go direcrt (if someone has windows server)
I made my cache to 1000k and still had the problem,
1000k cache would fill in less than a minute