A. Hierarchical OSPF networks need to be in one area
B. Multiple OSPF areas must connect to area 0
C. Single area OSPF networks must be configured in area 1
D. Areas can be assigned any number from 0 to 63535
E. Area 0 is called the backbone area
F. Each OSPF area need to be configured with a loopback interface

A. It confines network instability to a single area of network.
B. It increases the routing overhead of the network
C. It supports VLSM
D. It routes between Autonomous Systems.
E. It allows extensive control of routing updates
F. None of the above