Do I have to pay child support if I dispute paternity?

My ex is coming after me for child support but I do not think I am the father of the baby. I learned after we broke up that she was not faithful to me so I question paternity at this time. She has filed paperwork with the court and I only have a certain amount of time to file an answer. I need to know how to respond to her request for support and whether I can dispute paternity at the same time. What do I need to do to have a paternity test court ordered and am I required to pay any child support while the paternity matter is pending?