Quick Answer

The correct match for Weighted Tail-drop is "Drops packets based on a per-class drop threshold but still drops all when threshold exceeded." This mechanism combines the simplicity of tail-drop with class-based differentiation: each class has its own queue threshold, and once that threshold is reached, all subsequent packets for that class are dropped until the queue recovers. Unlike standard tail-drop, which drops indiscriminately when the single queue is full, Weighted Tail-drop allows higher-priority classes to retain buffer space longer. On the ENCOR 350-401 exam, this topic tests your ability to distinguish between congestion avoidance mechanisms like RED, WRED, and ECN, often in drag-and-drop or scenario-based questions. A common trap is confusing Weighted Tail-drop with WRED—remember that WRED uses probabilistic early dropping based on IP precedence or DSCP, while Weighted Tail-drop is a hard threshold drop per class. Memory tip: "Weighted Tail-drop is a hard stop per class; WRED is a soft warning per class."