The Define host name-to-Kerberos realm mappings machine setting should be configured correctly. This policy setting allows you to specify which DNS host names and which DNS suffixes are mapped to a Kerberos realm. If you enable this policy setting, you can view and change the list of DNS host names and DNS suffixes mapped to a Kerberos realm as defined by Group Policy. To view the list of mappings, enable the policy setting and then click the Show button. To add a mapping, enable the policy setting, note the syntax, and then click Show. In the Show Contents dialog box in the Value Name column, type a realm name. In the Value column, type the list of DNS host names and DNS suffixes using the appropriate syntax format. To remove a mapping from the list, click the mapping entry to be removed, and then press the DELETE key. To edit a mapping, remove the current entry from the list and add a new one with different parameters. If you disable this policy setting, the host name-to-Kerberos realm mappings list defined by Group Policy is deleted. If you do not configure this policy setting, the system will use the host name-to-Kerberos realm mappings that are defined in the local registry, if they exist. Fix: (1) GPO: Computer Configuration\Administrative Templates\System\Kerberos\Define host name-to-Kerberos realm mappings (2) KEY: HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\domain_realm_Enabled