多项选择题 What kind of information does a router running a link-state routing protocol need to create and maintain its topological database?（）

单项选择题 In a point-to point network, which address are OSPF hello packets sent to?（）

单项选择题 The Testking router is running both RIP and IGRP, and the same route is learned by this router from both of these methods. However, when you issue the command"show ip route" you see only the IGRP route, and not the RIP route. Why is this?（）