Your network contains an Active Directory domain named contoso.com. The network is configured to use ISATAP.You have a server named Server1 that runs Windows Server 2008 R2.On Server1, you discover that a tunnel adapter named isatap.contoso.com has a Media State of Media disconnected.You confirm that Server1 has a valid network connection and can query the DNS server.You need to ensure that the isatap.contoso.com tunnel adapter has an IPv6 address.What should you do？（）

• A、Start the IP Helper service.
• B、Start the IPsec Policy Agent service.
• C、Add a new rule to Windows Firewall.
• D、Add an entry for ISATAP to the Hosts file.