A.route ip 172.0.0.0 255.0.0.0s0 B.ip route 0.0.0.00.0.0.0 172.16.20.1 C.ip route 0.0.0.0255.255.255.255 172.16.20.1 D.route ip 0.0.0.0255.255.255.0 172.16.10.1150
A.163 B.126 C.139 D.179
A.区域内路由 B.区域间路由; C.第一类外部路由 D.第二类外部路由
A.1024 B.2046 C.4094 D.4096
A.BGP B.IS-IS C.RIP D.OSPF
A.0.0.0.1 B.0.0.0.0 C.255 D.255.255.255.255
A.禁止 B.允许 C.都不是