单项选择题
For security reasons, the network administrator needs to prevent pings into the corporate networks from hosts outside the internetwork. Which protocol should be blocked with access control lists（）。
A.IP B.ICMP C.TCP D.UDP
单项选择题 对于一个没有经过子网划分的传统C类网络来说，允许安装多少台主机？（）
单项选择题 下列哪一个命令用于指定物理接口做备份接口？（）
多项选择题 Which two features did WPAv1 add to address the inherent weaknesses found in WEP?（）
