Question: In indirect communication scenarios between NF Service Producer and NF Service Consumer, what type of authentication is used by relying on the transport layer protection solution?
Option 1: Explicit mutual authentication
Option 2: Implicit authentication with hop-by-hop security
Option 3: Token-based authorization only
Option 4: Implicit authentication provided by NDS/IP or physical security
Explanation: In indirect communication scenarios, the NF Service Producer and NF Service Consumer use implicit authentication by relying on authentication between NF Service Consumer and SCP, and between SCP and NF Service Producer, provided by the transport layer protection solution, NDS/IP, or physical security. This is because mutual authentication between NF Service Consumer and NF Service Producer is not achieved with hop-by-hop security.