Your network consists of a single Active Directory domain named contoso.com. All network servers run Windows Server 2003 Service Pack 2 (SP2).You have a DNS zone named contoso.com. The zone is configured to support dynamic updates. All servers in the company are registered in the contoso.com zone. You change the IP address of a server named Server1. From a server named Server2, you attempt to ping Server1 by host name, but the request fails. You successfully ping the new IP address of Server1.You need to ensure that Server2 can connect to Server1 by using the Server1 host name.  Which two actions should you perform?（）

• A、On Server1, restart the Netlogon service. 
• B、On Server2, run the Ipconfig /flushdns command. 
• C、On Server1, run the Ipconfig /Registerdns command. 
• D、On the DNS server, run the Dnscmd /zonerefresh contoso.com command.