求救！~~~~~````
RouterA用串口s0通过网络云连接RouterB的S1口，但RouterA的一端是DTE端
以下是题目，还望指教！~
RouterA#show interface s0
serial 0 is up ,line protocol is down
hardware is HD64570
Interface address 10.1.1.1
encapsulation HDLC ,loopback not set,keepalive set (10 sec)
routerA is unalbe to connect to routerB ,which is a nortel router;through the network cloud ,using the command output shown what must be configured on routerA's interface so to change the line protocol from down to up?
A:no shutdown
B:encapsulation ppp
C:interface serial point-to point
D:clock rate 56000
answer:B
但我觉得B像是不对，因上面已显示了封装类型为HDLC我想不用再封装了吧，思科的默认封装也是HDLC
但A我认为也不对啦，因Serial 0 is up的，所以端口不可能是关闭的，D也不对啦，因是DTE端是不用设置时钟的C也是不对的，所以我不知道答案是什么，但这些答案看起来好像还是B要好点！~~~~~~~~还望指教！~~~~~~
2 cisco supports IPX traffic using different encapsulation types can go over the same interface
A True
B False
答案是什么啦？？
