Question: What is a mandatory security feature for the reference point Zh between the Bootstrapping Server Function (BSF) and the Home Subscriber Server (HSS), according to 3GPP Generic Authentication Architecture (GAA) requirements?
Option 1: Mutual Authentication, Confidentiality, and Integrity
Option 2: Encryption Only for User Data
Option 3: Secure Key Exchange without Authentication
Option 4: Regular Time-Stamped Security Audits
Explanation: The correct answer is Option 1 because the requirements explicitly state that mutual authentication, confidentiality, and integrity are mandatory to ensure secure communication between the BSF and HSS, protecting against various threats and ensuring the integrity of bootstrapping information and subscriber security settings.