Question: What happens when a Conditional (C) Information Element is present in a Diameter command but its required conditions are not fulfilled?
Option 1: The receiver ignores the Information Element without any error.
Option 2: An application error occurs, triggering a response with Result-Code set to DIAMETER_MISSING_AVP.
Option 3: An application error occurs, and a response is sent back with Result-Code set to DIAMETER_AVP_NOT_ALLOWED, including a Failed-AVP AVP.
Option 4: The command is automatically rejected without further processing.
Explanation: According to the specifications for handling Information Elements in Diameter commands, if a Conditional (C) Information Element is included when its conditions are not met, it triggers an application error. The receiver responds with a Result-Code of DIAMETER_AVP_NOT_ALLOWED and includes a Failed-AVP AVP containing a copy of the offending Diameter AVP.