You have a DNS server named Server1 that runs Windows Server 2003 Service Pack 2 （SP2）. Server1 hosts a primary zone for contoso.com. On Server1， you update the host （A） record for server2.contoso.com to have a new IP address. On Server1， you run Ping server2.contoso.com from a command prompt and the old IP address for Server2 is returned.You need to ensure that the new IP address for Server2 resolves correctly on Server1. What should you do？（）

A. Run Nbtstat –
B. Run Ipconfig /flushdns.
C. Restart the DNS Server service.
D. Open the DNS snap-in， right-click on the server and click Clear Cache.