Which policy-map action performs congestion avoidance?

A.
priority

B.
bandwidth

C.
queue-limit

D.
random-detect

Explanation:
Congestion avoidance techniques monitor network traffic loads in an effort to anticipate and avoid
congestion at common network bottlenecks. Congestion avoidance is achieved through packet
dropping. Among the more commonly used congestion avoidance mechanisms is Random Early
Detection (RED), which is optimum for high-speed transit networks. Cisco IOS QoS includes an

implementation of RED that, when configured, controls when the router drops packets. If you do not
configure Weighted Random Early Detection (WRED), the router uses the cruder default packet drop
mechanism called tail drop.

http://www.cisco.com/c/en/us/td/docs/ios/12_2/qos/configuration/guide/fqos_c/qcfconav.html