如何實現(xiàn)擁塞避免？

aaa架構中哪個是要求用戶輸入用戶名和密碼？

four switches， which one will be root switch.（no pic）.

R1 will choose which path to reach 10.1.0.0？

The Frame Relay network in the diagram is not functioning properly.What is the cause of the problem?（） 

Which of the following are key characteristics of PPP?（）

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?（）

How should arouter that is being used in a Frame Relay network be configured to avoid split horizon issues from preventing routing updates?（）

what is the disadvantage of policing？

Refer to the exhibit.The network administrator is in acampus building distant from Building B.WANRouter is hosting a newly installed WAN link on interface S0/0.The new link is not functioning and the administrator needs to determine if the correct cable has been attached to the S0/0 interface.How can the administrator accurately verify the correct cable type on S0/0 in the most efficient manner?（）