When an application attempts to make a remote procedure call (RPC) to this server with a NULL value for the service principal name (SPN), computers running Windows 7 will attempt to use Kerberos by generating an SPN. This policy setting allows you to configure this server so that Kerberos can decrypt a ticket that contains this system-generated SPN.
If you enable this policy setting, only services running as LocalSystem or NetworkService will be allowed to accept these connections. Services running as identities different from LocalSystem or NetworkService might fail to authenticate.
If you disable or do not configure this policy setting, then any service will be allowed to accept incoming connections by using this system-generated SPN.