How to configure NT DNS for internet?

I’m an admin at a new place. They have two NT servers handling all Dns requests for the entire network’s intranet and Internet needs. It also handles all requests for the company .com domain name. These two servers have IP addresses on the internet and so do all the clients(I know, big risk). BUT

What I can’t seem to understand is how are these two servers able to resolve internet DNS queries? I am thinking it must connect to some higher level DNS servers. But I can’t seem to see wherethis is set in the dns admin. Also if so, is my company paying some provider to allow us to handle our own Dns requests?