单项选择题
Which line from the output of the show ip interface command indicates a layer 1 problem?（）
A. Serial0/1 is up, line protocol is down B. Serial0/1 is down, line protocol is down C. Serial0/1 is up, line protocol is up D. Serial0/1 is administratively down, line protocol is down
单项选择题 Which statement about IPv6 is true?（）
单项选择题 Which statement about RIPng is true?（）
单项选择题 Which term describes the process of encapsulating IPv6 packets inside IPv4 packets?（）
