I have always manually set my IP and DNS on the client side because of all the port forwarding I do. So if push comes to shove just determine what your DNS addresses are (either ipconfig when it is working or login to the router to find out) and just manually define them.
Where you define it is in Network Connections, right click on the device your using > Select Internet Protocol (TCPIP) (or Version 4 TCP/IPv4 for Vista and W7) > Properties
However most DNS or network issue can be fixed by either disabling/enabling your network device or restarting your router