A.network190.72.27.0 B.network190.72.27.0mask255.255.255.224 C.network190.72.27.0255.255.255.240 D.network190.72.27.0255.255.255.224 E.network190.72.27.00.0.0.31
A.路由器R2是DR或者BDRB.路由器R3不是DR或者BDRC.路由器R2和路由器R3的邻接关系还没完全建立(没到FULL)D.路由器R2不是DRE.路由器R4是DR