Split horizon has been enabled within the Ezonexam routed network. Which one of the following statements best explains the split horizon rule?
A、Only routers can split boundaries (horizons) between networks in separate AS numbers.
B、Each AS must keep routing tables converged to prevent dead routes from being advertised across boundaries.
C、Once a route is received on an interface, advertise that route as unreachable back out the same interface.
D、Information about a route should never be sent back in the direction from which the original update came.
E、None of the above
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试题解析
解析：Explanation:The split horizon rule states:* Never advertise a route out of the interface through which you learned it.For instance, in Figure 4a below, if Router One is connected to Routers Two and Three through a single multipoint interface (such as Frame. Relay), and Router One learned about Network A from Router Two, it will not advertise the route to Network A back out the same interface to Router Three. Router one assumes that Router Three would learn about Network A directly from Router Two.Incorrect Answers:A: There is no such requirementB: Distance vector protocols updates routing table at regular intervals instead of Topology changesC: This is the definition of the poison reverse rule, not the split horizon rule.
