1. [多选题]对于IP为199.41.27.0，子网掩码为255.255.255.240，则该IP地址和子网掩码相作用会得到一系列IP，从下列选项中选出属于“有效IP”的选项：()
A. 199.141.27.33
B. 199.141.27.112
C. 199.141.27.119
D. 199.141.27.126
E. 199.141.27.175
F. F.199.141.27.208
2. [单选题]如果把路由器的某个端口的IP配置为：192.168.10.64，掩码配置为：255.255.255.248，则该端口（）
A. 能和其他设备正常通信
B. 会变成“administratively down”状态
C. 端口被烧毁
D. 出现错误提示，配置命令执行失败
3. [多选题]Two stations on the Ezonexam LAN transmit at the same time, resulting in a collision. What happens when a collision occurs on the network? (Choose all that apply)
A. Each device on the Ethernet segment stops transmitting for a short time.
B. A jam signal informs all devices that a collision occurred.
C. When data transmission resumes, the devices that were involved in the collision have priority to transmit.
D. The devices that are involved in the collision stops transmitting for a short time.
E. The collision invokes a random back-off algorithm.
