It’s Politics 101: If you’re going to put up a website attacking your opponent, don’t forget to spend a few bucks and buy the URL to keep it out of anyone else’s hands.

Gov. Andrew Cuomo’s campaign surrogates forgot that basic rule when they posted MolinaroShadydeals.com to allow people to report negative information about Republican rival Marc Molinaro.

The Dutchess County Democratic Committee issued a press release Sunday announcing that it had opened a “tip line” — MolinarosShadyDeals.com — to expose alleged misdeeds by Molinaro, the Dutchess County executive who is challenging Cuomo’s bid for a third term.

But anyone who clicked on MolinarosShadyDeals.com was directed to a different site — CuomoLeaks.com.

That’s the WikiLeaks-type site the Molinaro campaign set up last week urging New Yorkers to “blow the whistle on corruption” in the Cuomo administration.

The Molinaro campaign confirmed that it had bought rights to the MolinarosSheadyDeals.com URL and repurposed it to its site slamming Cuomo on corruption.