A.Queuing introduces equal delays for packets of the same flow， resulting in jitter.
B.When congestion occurs， dropping affects most of the TCP sessions， which simultaneously back off and then restart again.
C.All buffers can temporarily be seized by aggressive flows， and normal TCP flows experience buffer starvation.
D.There is no differentiated drop mechanism. Higher priority traffic is dropped in the same way as best-effort traffic.
E.In TCP starvation， traffic exceeds the queue limit because of the bursty nature of packet networks. A router cannot handle multiple concurrent TCP sessions.
F.Global synchronization occurs because multiple TCP hosts reduce their transmission rates at random intervals in response to packet dropping

A. If the classification policy is based upon the ToS byte， the qos pre-classify command is required because the ToS byte only appears in the inner IP header.
B. The ToS byte is copied to the outer header by default. Therefore， the qos pre-classify command is not necessary.
C. With GRE encapsulation， the qos pre-classify command is applied on the tunnel interface. This practice allows for different OoS configurations on each tunnel.
D. With GRE encapsulation， the qos pre-classify command is applied on the physical interface. This practice allows for different OoS configurations on each interface.
E. With IPsec encapsulation， the qos pre-classify command is applied on the physical interface. This practice allows for different OoS configurations on each interface.