单项选择题
You are the network administrator of a Layer 3 switched network. Users in one VLAN are complaining that access to the server VLAN is very slow from time to time. Traffic in the local VLAN works without any issue， and users in other VLANs do not have any complaint to reach the server VLAN. What is most likely the cause of this issue？（）
A.routing issue B.denial-of-service attack C.MAC flooding D.spanning-tree recalculation E.Layer 2 loop F.ARP spoofing attack
多项选择题 WhichthreeprotocolsshouldbeexplicitlymanagedbyusingControlPlanePolicingonanInternetborderrouter？（）
单项选择题 WhichQoSmechanismcanhelpclassifydifferentkindsofCitrixtraffic（printjobversusreal-timeterminalcontrol）？（）
单项选择题 WhichstatementiscorrectaboutanOSPFsham-link？（）
