单项选择题
A.170.18.128.0/21 B.170.18.128.0/22 C.170.18.130.0/22 D.170.18.132.0/23
A.115.17.198.0 B.115.17.206.0 C.115.17.217.0 D.115.17.224.0
A.1024 B.1023 C.1022 D.1000