How to configure 2 network cards

[abrtityd01]

I need to setup two network cards, one for the domain network and another one for Internet access.

If I have both network card connected the Internet access goes thru the Domain Card, if I unplug the domain card the Internet access goes for that card and it is wath i need.
But Again if I reconnect the domain network card the Internet access trafic going from this domain card. ¿How can I select wich card I prefer to sent the trafic for?

Regards