For various of reasons you may need to block Google DNS access in your network. For example some applications like Netflix on Chromecast are set to use Google DNS default in the application. So in order to make these apps to work properly you need to block Google DNS access in your Tomato Router.
Tomato routers have a very simple way of redirecting traffic queries from Google DNS to your router default DNS (Smart DNS Proxy).
1. Login to Tomato Router Admin Panel
2. Click Advances > DHCP/DNS option
3. Check the checkbox "Intercept DNS port 53".
4. Click Save
Now all DNS queries will be routed to your Tomato Router Default DNS. This includes Google DNS and any other services.
In order to use Tomato Router with Smart DNS Proxy, make sure to setup your Tomato Router. You can find Tomato router dns setup instructions here.
Remember to visit Smart DNS Proxy MyAccount section and check if your IP address is registered. Many of the Internet Service Providers changes IP address of the modem/router when it's restarted.