多项选择题
A.Each router has an identical link state database
B.External routes are imported into a separate link state database
C.Synchronization of link state databases is maintained via flooding of LSAs
D.Information in the link state database is used to build a routing table by calculating a shortest-path tree
E.By default， link state databases are refreshed every 10 minutes in the absence of topologychanges
单项选择题 DR （Designated Router） is for environments where many routers on the same network such asEthernet. In the following presented network， all routers are reloaded simultaneously， and DR isselected as expected. What is the CK-RTC status？（）
多项选择题 Which three of the following network features are methods used to achieve high availability（）
单项选择题 Refer to the exhibit. On the basis of the information presented， which statement is true？（）