Local DNS very very slow

Hi

We have a LAN with about 10 machines in MS Active directory 2003 environment. Domain Controller has build-in DNS server. Few days ago I set up a new Linux Oracle machine in LAN, but not as AD member. DNS resolution from local DNS server from that machine is very slow. When I change settings to external public DNS from Google, everything works perfectly. So in my view the problem is on the side of DNS server. Could you point me how can I solve that problem to work with local DNS?
I tried to get websites from browser and with wget. Both works very pooorly with local DNS.


Thanks