dns server consuming more ip bandwidth

i have configured a win2k server asa active directory domain controller which is the root domain of the tree, and is registered in network solutions and pointed to this server. Initially planned the dns server is not connected to any of the clients,and this server is consuming lot of bandwidth, why the server is consuming that much bandwith or is there any thing wrong in the configuration. In addtion to this my dns server is configured as forwarding external dns traffic to the isp dns server.How i can stop the server for consuming internet bandwidth.