单项选择题
A.ip verify unicast source reachable-via any
B.ip verify unicast reverse-path
C.ip verify unicast reverse-path loose
D.ip verify unicast reverse-path strict
单项选择题 Beforeinsertinganewswitchinthenetwork，thenetworkadministratorchecksthattheVTPdomainnameiscorrect，theVTPmodeissettoserver，andrevisionislowerthantheswitchesinthenetwork.Theadministratorthenconfiguresinterfacesandtrunks，erasesexistingVLANs，andconnectstheswitchtothenetwork.Followingthatprocedure，thereisnoconnectivityinthenetwork.Whatisapossiblecauseofthisproblem？（）
多项选择题 Refer to the exhibit. Users from the Engineering VLAN complain that every time Business VLAN users have a network connectivity issue， the Engineering VLAN users usually have problems experiencing slow response or network connectivity problems. After troubleshooting， an unauthorized switch 2 was found. This unauthorized switch has been a regular problem， assuming the root bridge function under the spanning-tree domain and causing the Engineering VLAN to be unstable. Which three of these actions could be suggested to fix the problem？（）
单项选择题 WhatistrueaboutIPSourceGuardwithportsecurity？（）