[nsp] dns forwarding

[Roger]

I'm working on replacing a customer router w/ a 1605.  The previous 
router acted as a dns-caching server, something that a 1605 does not do.

In order for this router to be a drop in replacement dns queries going 
to the internal address need to be passed along to the external dns server.

I've tried the below configuration w/o success.

inter eth0
ip address <public ip>
ip nat outside
!
inter eth1
ip address 192.168.0.1 255.255.255.0
ip nat inside
!
ip nat outside source static udp <public_ip_eth0> 53 <ip of dns server> 
53 ext
ip nat inside source list internal interface Ethernet0 overload
!
ip access-list standard internal
 permit 192.168.0.0 0.0.0.255

I realize repointing dns entries on the dhcp server would be the easiest 
and quickest solution.  This is kinda out of the question.

Any suggestions???