单项选择题
A.area 0.0.0.0{ linkneighbor-id 172.168.18.2 transit-area 0.0.2.1；}
B.area 0.0.0.0{ virtual-linkneighbor-id 172.168.18.2 transit-area 0.0.2.1；}
C.area 0.0.0.1{ virtual-linkneighbor-id 172.168.18.2 transit-area 0.0.2.1；}
D.area 0.0.2.1{ virtual-linkneighbor-id 172.168.18.2 transit-area 0.0.0.0；}
多项选择题 InJUNOSsoftware，whataretwowaystherouterIDischosen？（）
单项选择题 InJUNOSsoftware，whatisrequiredtodedistributeRIProutesintoOSPF？（）
单项选择题 AnOSPFnon-backboneareafollowsexternalroutestobefloodedwithinthearea.Theseexternalroutesarepropagatedintootherareas.However，externalroutesfromotherareasarenotallowedtoenterthisarea.WhichtypeofOSPFareadoesthisdescribe？（）