The Netlogon service on the domain controller registers a number of records in DNS that enable other domain controllers and computers to find Active Directory-related information. If the domain controller is pointing to the Internet service provider's (ISP) DNS server, Netlogon does not register the correct records for Active Directory, and errors are generated in Event Viewer. In Windows Server 2003, the recommended DNS configuration is to configure the DNS client settings on all DNS servers to use themselves as their own primary DNS server, and to use a different domain controller in the same domain as their alternative DNS server, preferably another domain controller in the same site. This process also works around the DNS "Island" problem in Windows 2000. You must always configure the DNS client settings on each domain controller's network interface to use the alternative DNS server addresses in addition to the primary DNS server address.