No, you don't want the routing interface. You want to control DNS, not routing (routing controls what happens when you try to communicate with a...
Like Nimrod said, there's a good chance your router doesn't support the feature. My own doesn't with the default firmware. DD-WRT, Tomato,...
Just came across this thread doing a Google search on this topic. It looked like too much manual effort though, so I kept looking and came across...
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