简答题 What’s PHB？

单项选择题Whatarethemandatory，well-knownBGPattributes？（）

A.origin,AS-path,next-hop
B.AS-path,origin,MED
C.AS-path,origin,weight
D.AS-path,weight,MED

问答题R1收到组播信息而R2收不到，why？

单项选择题YouuseOSPFasyournetworkroutingprotocol.YouusethecommandshowiprouteandyouseeseveralroutesdescribedasO，OIA，OE1，andOE2.Whatroutesareinyourarea？（）

A.O IA
B.O E1
C.O E2
D.O

单项选择题YourCisconetworkcurrentlyrunsOSPFandyouhaveaneedtopolicy-routesomespecifictraffic，regardlessofwhattheroutingtableshows.Whichoneoftheseoptionswouldenableyoutopolicy-routethetraffic？（）

A.source IP address and the protocol （such as SSL， HTTPS， SSH）
B.the packet Time to Live and the source IP address
C.type of service header and DSCP value
D.destination IP address

单项选择题Refer to the exhibit. Routers A and B are directly connected and running OSPF， but they are unable to form a neighbor relationship. What is the most likely cause？（）

A.The routers are not on the same network.
B.The network statements do not match.
C.The process number does not match.
D.The MTU does not match.
E.The OSPF cost does not match.
F.There is a physical issue with the cable.