Final answer:
RADIUS is recommended to be run only on isolated administrative networks due to its security vulnerabilities. Kerberos is a safer alternative, using a ticketing system and strong cryptography, but all authentication services should be used within controlled environments to protect data integrity.
Step-by-step explanation:
The authentication protocol that is recommended to be run only on isolated administrative networks is Remote Authentication Dial-In User Service (RADIUS). RADIUS is a networking protocol that provides centralized Authentication, Authorization, and Accounting management for users who connect and use a network service. However, due to its security vulnerabilities, such as susceptibility to packet interception and replay attacks, it is advised to be used within controlled environments. This secure usage ensures that sensitive information transmitted during the authentication process is not accessible to malicious entities.
Kerberos is another example of an authentication protocol that is more secure than RADIUS, as it uses a ticketing system and strong cryptography to ensure safer authentication processes. In any case, when setting up a network with authentication services, it's critical to ensure that it's deployed on an isolated network to protect against external threats and maintain the integrity of the authentication process.