问答题 The interface is up and protocol is up. When do u get these messages.

问答题 TwoCiscoroutersareconnectedtoeachotherandareenabledCDP.Seriallineisup，protocolisalsoupbutcdpneighbornotworking.WhatlayeroftheOSImodeldoestheproblemmostlikelyexist？

单项选择题 The interface is up and protocol is up. What level of logging is enabled when you get these messages？（）