Instructions
Select the "Settings" icon at the PS3's main menu. Press the "X" button on the controller, and then press "X" again at the "Network Settings" icon.
Select "Internet Connection Settings," and then select "Yes" when prompted. The PS3 console will temporarily disconnect from the Internet while you're editing the connection settings.
Select "Custom" at the next screen and choose "Wired Connection" or "Wireless Connection," depending on the type of connection used. Use the directional pad to scroll through the custom settings until you see "DNS Setting."
Press the "X" button to select "DNS Setting" and select "Manual." The primary and secondary DNS should appear on-screen.