Question: What is the requirement for a UE to support EAP-based secondary authentication and authorization by a DN-AAA server over EPC in the context of establishing a PDN connection?
Option 1: It is mandatory for the UE to support EAP-based secondary authentication and authorization.
Option 2: It is optional for the UE to support EAP-based secondary authentication and authorization.
Option 3: The UE must support EAP-based secondary authentication but not authorization.
Option 4: The UE must support authorization but not EAP-based secondary authentication.
Explanation: According to the principles outlined, it is optional for the UE to support EAP-based secondary authentication and authorization by a DN-AAA server over EPC. This means that the UE may or may not support this feature, and its implementation is not mandatory.