单项选择题 You have an Active Directory domain named contoso.com.   You have a domain controller named Server1 that is configured as a DNS server.   Server1 hosts a standard primary zone for contoso.com. The DNS configuration of Server1 is shown in  the exhibit. （Click the Exhibit button.）   You discover that stale resource records are not automatically removed from the contoso.com zone.   You need to ensure that the stale resource records are automatically removed from the contoso.com  zone.   What should you do（）

单项选择题 Your network contains a domain controller that is configured as a DNS server. The server hosts an  Active Directory-integrated zone for the domain.   You need to reduce how long it takes until stale records are deleted from the zone.  What should you do（）

单项选择题 Your network contains an Active Directory domain named contoso.com. The domain contains the servers shown in the following table.   Server name  Operating system  Role   DC1  Windows Server 2008  Domain controller    DC2  Windows Server 2008 R2  Domain controller    DNS1  Windows Server 2008  DNS server  DNS2  Windows Server 2008 R2  DNS server   The functional level of the forest is Windows Server 2003. The functional level of the domain is Windows  Server 2003.   DNS1 and DNS2 host the contoso.com zone.   All client computers run Windows 7 Enterprise.   You need to ensure that all of the names in the contoso.com zone are secured by using DNSSEC.  What should you do first（）