单项选择题 如下图，两个路由器（Atlanta和Brevard）用串口连接起来。但是他们之间没有数据传输，已知Atlanta配置正确，下图给出部分配置，路由器Brevard上导致该问题的原因是（）。

单项选择题 You have finished physically installing an access point on the ceiling at your officE.At a minimum, which paramenter must be configured on the access point in order to allow a wireless client to operate on it?（）

单项选择题 At which OSI layer is a logical path created between two host systems（）。