Old NS Records Still Showing Up

[kickballmvp2006]

I have a test domain environment that was set up to mimic production. On this test environment I have two domain controllers in my child domain and two in the parent. When I do an nslookup on the child domain I see the two DNS servers that are currently there, but I also see the DCs that were there from the production environment that I cloned. When I go the forward lookup zone for the child domain and look at the NS records, the only ones I see are for the two child domain controllers and two parent domain controllers. I made sure to delete the ones that were not needed but still I see all domain controllers when I do nslookup. I'm wondering how to clear these old records out.