Netopia 435 Reference Manual page 87

4-22 Netopia ISDN Router Reference Guide
Select Serve DNS Servers, toggle to Yes, and press Return. By
toggling this item to Yes, once the DNS Server's IP address or
addresses (Primary and Secondary DNS Server IP Address) are
entered the Netopia ISDN Router will automatically broadcast this
information to the client machine. (Note that you will need to
configure each client machine for the Netopia ISDN Router).