什么是NAT？

what is the advantage of policing opposite to shaping？

As a CCNA candidate,you must have a firm understanding of the IPv6 address structure.Refer to IPv6 address,could you tell me how many bits are included in each filed?（）

QoS Mechanisms：問在部署QoS中要用的3個mechanisms是什么？

Refer to the exhibit.How many broadcast domains exist in theexhibited topology？（）

如何實現(xiàn)擁塞避免？

QoS機制中的分類，采用ip數(shù)據(jù)包中的哪個字段？

當將多個交換機加入到MST region當中會發(fā)生什么（what happen）？

Local Preference？

The following configuration line was added to router R1 Access-list 101 permit ip 10.25.30.00.0.0.255 any What is the effect of this access list configuration?（）