What protocol should Angela monitor to read traffic from a RADIUS server configured with default settings?

To effectively monitor traffic from a RADIUS server configured with default settings, it is essential to focus on the correct transport protocol used by RADIUS. RADIUS (Remote Authentication Dial-In User Service) primarily operates over the User Datagram Protocol (UDP). This choice is due to UDP's nature, which allows for faster transmission of information without the overhead of connection establishment and error-checking that TCP entails.

RADIUS typically uses UDP port 1812 for authentication and 1813 for accounting, which aligns with its default configuration. Monitoring this UDP traffic allows for proper analysis of authentication requests and responses exchanged between the RADIUS server and its clients, such as network access devices (e.g., routers or switches).

Other protocols such as ICMP (Internet Control Message Protocol) and HTTP (Hypertext Transfer Protocol) do not pertain to RADIUS communications, making them irrelevant for this specific task. While TCP is a reliable protocol often preferred for established connections, it is not the correct choice for monitoring RADIUS traffic due to the latter's reliance on UDP for its operations. Thus, monitoring UDP is essential for tracking the relevant activities of a RADIUS server.