One of your remote Security Gateways suddenly stops sending logs, and you cannot install the Security Policy on the Gateway. All other remote Security Gateways are logging normally to the SmartCenter Server, and Policy installation is not affected. When you click the Test SIC status button in the problematic gateway object, you receive error message "unknown". What is the problem?

A.
The remote Gateway’s IP address has changed, which invalidates the SIC Certificate.

B.
The Security Gateway is NG with Application Intelligence, and the SmartCenter Server is NGX.

C.
The Internal Certificate Authority for the SmartCenter object has been removed from objects_5_0.C.

D.
The time on the SmartCenter Server’s clock has changed, which invalidates the remote Gateway’s Certificate.

E.
There is no connection between the SmartCenter Server and the remote Gateway. Rules or routing may block the connection.