Cisco Certified Internetwork Expert (CCIE) 2025 – 400 Free Practice Questions to Pass the Exam

In RADIUS (Remote Authentication Dial-In User Service) communications, the integrity of data packets is ensured by the use of an authenticator. The authenticator serves as a unique value that is calculated based on the content of the message, the secret shared between the client and server, and a timestamp. This means that if any part of the packet is altered during transmission, the authenticator will not match when it reaches its destination, indicating that the packet has been tampered with.

This mechanism effectively protects against certain attacks, such as packet sniffing and replay attacks, by providing a way to confirm that the message came from a legitimate source and has not been altered in transit. The importance of the authenticator in ensuring data integrity makes it a critical element in RADIUS communications.

The other choices do not specifically guarantee the integrity of the packets in the context of RADIUS. While the length might help in defining the packet structure, it does not ensure integrity. Message-Integrity-Check (MIC) is a term associated with different protocols, like EAP (Extensible Authentication Protocol), rather than RADIUS itself. Type of Service is related to the prioritization of traffic over a network rather than the integrity of the communication. Thus, the use