Cisco Certified Network Professional Practice Test

The command used to configure UDLD (Unidirectional Link Detection) in aggressive mode is "udld aggressive." This command is essential for enabling a specific functionality of UDLD that helps detect unidirectional links more effectively. When configured in aggressive mode, UDLD can proactively detect unidirectional links and take action to disable the incorrect link more quickly than in standard mode. This is crucial in environments where network availability and reliability are paramount, as it helps prevent potential network loops and ensures that traffic is flowing as intended. Other commands like "udld enable" activate UDLD generally across an interface but without specifying that it operates in aggressive mode. "udld disable" is used to turn UDLD off altogether, negating its functionality, while "udld message time seconds" adjusts the timing of UDLD message intervals but does not directly configure its operational mode. Thus, "udld aggressive" is the specific command that brings the desired aggressive detection behavior into play.