In the matters needing attention when configuring the NSSA area, which of the following description is correct?
A . The NSSA area can propagate external routes from other areas of the OSPF network.
B . The backbone area can be configured as an NSSA area.
C . Virtual connections can traverse the NSSA area.
D . If an area is configured as an NSSA area, all routers in the area must be configured as NSSA areas.
Answer: D