Cisco Certified Network Professional 2026 – 400 Free Practice Questions to Pass the Exam

The default time interval for UDLD (Unidirectional Link Detection) message transmission is indeed 15 seconds. UDLD is a link management protocol that helps detect and prevent unidirectional links, which can cause network issues by creating loops or dropping traffic. To maintain communication and check for link status, UDLD messages are sent out at regular intervals, and this default interval ensures that link statuses are monitored effectively without overwhelming the network with excessive messages.

Setting the interval to 15 seconds strikes a balance between timely detection of issues and efficient use of network resources, as overly frequent messages could lead to unnecessary load on the network devices without significantly improving detection speed.