ADSL with Active directory

WELL I’M WORKING TECHINACL SUPPORT. I FACED ONE PROBELM WITH WINDOWS 2000 SERVER AS A WORKGROUP, AFTER PROMOTING TO DOMAIN, INTERNET WAS STOP, I NOTICED THAT IT WASN’T TAKING ANY IP ADDRESS FROM ISP. IT WAS TAKING API ADDRESS. INTERNET WAS CONNECTEDFROM DSL MODEM. CLIENTS WHERE BROWSING FROM PROXY SERVER 2.0