A.Redirect
B.Sourcequench
C.Echoreply
D.estinationunreachable

A.route ip172.0.0.0255.0.0.0s0
B.ip route0.0.0.00.0.0.0172.16.20.1
C.ip route0.0.0.0255.255.255.255172.16.20.1
D.route ip0.0.0.0255.255.255.0172.16.10.1150

A.255.255.255.252
B.255.255.255.128
C.255.255.0.0
D.255.255.255.192

A.10.254.255.23
B.10.254.255.24
C.10.254.255.255
D.10.255.255.255

A.物理层
B.数据链路层
C.网络层
D.传输层

A.0—65535
B.0—65536
C.1—65536
D.1—65535

A.Time-to-Live（TTL）
B.HeaderChecksum
C.Identifier
D.HopCount

A.管理工作站
B.管理代理
C.上下报文
D.管理协议

A.OSPF
B.RIP
C.IS-IS
D.静态

A.255.255.255.0
B.255.255.255.228
C.255.255.255.192
D.255.255.255.224

A.目标网络
B.源地址
C.路由权值
D.下一跳