Is RADIUS a Cisco-proprietary protocol?

RADIUS, which stands for Remote Authentication Dial-In User Service, is indeed an open standard protocol. It was developed in the 1990s to provide centralized authentication, authorization, and accounting for users who connect and use a network service. The fact that it is an open standard means that it can be implemented by any vendor, not just Cisco, which allows for interoperability between different devices and systems from various manufacturers.

The widely accepted nature of RADIUS has led to its inclusion and support across numerous networking platforms and products, making it a vital component in securing network access. RADIUS facilitates secure access control by allowing users to be authenticated and authorized through a central server, thereby streamlining the management of user credentials.

The other choices suggest that RADIUS is proprietary to Cisco or that only certain features are proprietary, which does not reflect its official status as an open standard. While Cisco does utilize RADIUS in its products and may implement specific features tailored to its devices, this does not change the fundamental nature of RADIUS itself as an open standard technology.