单项选择题
How many simultaneous Telnet sessions does a Cisco router support by default?（）
A.1 B.2 C.3 D.4 E.5 F.6
单项选择题 Which of the following protocols use both TCP and UDP ports?（）
多项选择题 What statements are true regarding ICMP packets?（）
多项选择题 Which three address ranges are used for internal private address blocks as defined by RFC 1918?（）
