1. [单选题]备份路由器IOS的命令是：()
A. copy flash tftp
B. copy running-configt ftp
C. copy IOS tftp
D. copy startup-configt ftp
2. [单选题]关于静态NAT，下面（）说法是正确的。
A. 静态NAT转换在缺省情况下24小时后超时
B. 静态NAT转换从地址池中分配
C. 静态NAT将内部地址一对一静态映射到内部全局地址
D. CISCO路由器缺省使用了静态NAT
3. [单选题]Given that you have a class B IP address network range, which of the subnet masks below will allow for 100 subnets with 500 usable host addresses per subnet?
A. 255.255.0.0
B. 255.255.224.0
C. 255.255.254.0
D. 255.255.255.0
E. 255.255.255.224
