单项选择题
根据下图，R1能通告给R2的最有效的汇总是？（）
A.172.1.0.0/22 B.172.1.0.0/21 C.172.1.4.0/22 D.172.1.4.0/24 172.1.5.0/24 172.1.6.0/24 172.1.7.0/24 E.172.1.4.0/25 172.1.4.128/25 172.1.5.0/24 172.1.6.0/24 172.1.7.0/24
多项选择题 What are three IPv6 transition mechanisms?（）
单项选择题 Given the output of the Floor3 switch, what statement describes the operation of this switch（）。
单项选择题 Running both IPv4 and IPv6 on a router simultaneously is known as what?（）
