Question: What happens to previous authentication information when an S-CSCF receives a new REGISTER request and challenges it, according to 3GPP security standards for IP-based services?
Option 1: The S-CSCF updates the previous authentication information with new challenge details.
Option 2: The S-CSCF deletes any information relating to the previous authentication.
Option 3: The S-CSCF temporarily stores the previous authentication information for potential future use.
Option 4: The S-CSCF sends a notification to the UE (User Equipment) about the previous authentication's status.
Explanation: This is correct because, as per the described security protocol for IP-based services, when an S-CSCF receives a new REGISTER request and issues a challenge, it treats any prior authentication attempt as failed. Consequently, it removes all associated data from the previous authentication to ensure security integrity, potentially allowing for a response to the previous challenge before proceeding with the new authentication process. This approach ensures that only the most current authentication attempts are considered valid, enhancing network security.