If you enable this setting, it directs the RPC Runtime on an RPC server to restrict unauthenticated RPC clients connecting ...

If you enable this setting, it directs the RPC Runtime on an RPC server to restrict unauthenticated RPC clients connecting to RPC servers running on a machine. A client will be considered an authenticated client if it uses a named pipe to communicate with the server or if it uses RPC Security. RPC Interfaces that have specifically asked to be accessible by unauthenticated clients may be exempt from this restriction, depending on the selected value for this policy.

If you disable this setting or do not configure it, the value of Authenticated will be used for Windows XP and the value of None will be used for Server SKUs that support this policy setting. If you enable it, the following values are available:

--  "None" allows all RPC clients to connect to RPC Servers running on the machine on which the policy is applied.

--  "Authenticated" allows only authenticated RPC Clients (per the definition above) to connect to RPC Servers running on the machine on which the policy is applied. Interfaces that have asked to be exempt from this restriction will be granted an exemption.

-- "Authenticated without exceptions" allows only authenticated RPC Clients (per the definition above) to connect to RPC Servers running on the machine on which the policy is applied. No exceptions are allowed.

Note: This policy setting will not be applied unti the system is rebooted.