While troubleshooting some connectivity issues，you issue the “show ip ospf database”in order to ex amine the link state database. Which three of the statements below are true regarding the OSPF link state database（）
- AEach router has an identical link state database.
- BExternal routes are imported into a separate link state database.
- CSyn chronization of link state databases is maintained via floodingo f LSAs.
- DInformation in the link state database is used to build a routing table by calculating a shortest-path tree.
- EBy default,link state databases are refreshede very 10 minutes in the absence of topology changes.