单项选择题 Refer to the diagram. Which OSPF configuration command is required to configure Area 3 a s atotally stubby area?（）

单项选择题 The Dev - 1 and Dev -3 routers are OSPF neighbors over the Ethernet 0/0 connection. Based on the show ip ospf neighbor output from the Dev - 1 and Dev - 3 routers, which statement is true?（）

单项选择题 During a recent OSPF election among three routers, RTA was elected the DR and RTB was elected the BDR, as seen in the graphic. Assume that RTA fails, and that RTB takes the place of the DR whi le RTC becomes the new BDR. What will happen when RTA comes back online？（）