What are the two distinct service modes offered by vAAA?

The correct choice identifies the two distinct service modes offered by vAAA—blockchain-based and OAUTH2.0 service. In the context of vAAA, which stands for virtual Authentication, Authorization, and Accounting, these modes represent different methodologies for handling authentication and authorization processes in an IoT environment.

Blockchain-based services are vital as they provide a decentralized and secure way to manage identities and transactions. This is increasingly significant in IoT, where numerous devices interact with sensitive data and need a robust mechanism for ensuring trust and reliability.

On the other hand, OAUTH2.0 is a widely adopted protocol that enables secure delegated access, allowing users to grant third-party applications limited access to their resources without exposing their credentials. This standard is prevalent in modern web and mobile applications, fostering interoperability and enhancing user experience while maintaining security.

The other options, while representing protocols or methods relevant to the wider field of networking and Internet technologies, do not capture the unique service modes provided specifically by vAAA, thereby distinguishing it within the IoT infrastructure landscape.