单选题An OSPF non-backbone area allows external routes to be flooded within the area. These external routes are propagated into other areas. However， external routes from other areas are not allowed to enter this area. Which type of SPF area does this descri
题目
单选题
An OSPF non-backbone area allows external routes to be flooded within the area. These external routes are propagated into other areas. However， external routes from other areas are not allowed to enter this area. Which type of SPF area does this describe？（）
A
stub area
B
transit area
C
border area
D
not-so-stubby area