（3）mail.test.com（4）B（5）D
A.everyone B.administrators C.powerusers D.users
A.ping192.168.1.100-a B.ping192.168.1.100-n C.ping192.168.1.100-t D.ping192.168.1.100-w
A.tracertcorp7.microsoft.com B.routecort7.microsoft.com C.pingcorp7.microsoft.com D.netstatcorp7.microsoft.com
（7）B
A.检查网络连接电缆 B.检查网卡的工作状态 C.检查DNS服务器地址配置 D.查杀病毒
（8）B
A.215.155.3.190 B.8.8.8.8 C.252.117.112.3 D.152.50.255.1
A.8 B.12 C.24 D.48
