
Refer to the exhibit After an engineer modified the configuration for area 7 to permit type 1 2 and 7 LSAs only users connected to router R9 reported that they could no longer access the internet. Which configuration restores internet access to users on R9 and permits only LSA type 1,2, and 7?
Correct Answer: B
Option B configures area 7 as a not-so-stubby area (NSSA) with the no-summary option on the area border router (ABR) R4. This allows the injection of external routes from EIGRP into the OSPF domain as type 7 LSAs, while preventing the propagation of inter-area summary LSAs into area 7. The no-summary option also generates a default summary route for area 7, which can be used by R9 to reach the internet2.
Option A configures area 7 as a stub area, which does not allow any external routes or type 7 LSAs in the area. This prevents R9 from learning the EIGRP routes and accessing the internet3.
Option C configures area 7 as a NSSA without the no-summary option on R4. This allows the injection of type 7 LSAs into the area, but also allows the propagation of inter-area summary LSAs into the area. However, this option does not generate a default summary route for area 7, which means R9 has no route to reach the internet4.
Option D configures area 7 as a NSSA with the default-information originate option on R4. This allows the injection of type 7 LSAs into the area, but also allows the propagation of inter-area summary LSAs into the area. The default-information originate option generates a type 7 default route for area 7, which can be used by R9 to reach the internet. However, this option is redundant and less efficient than Option B, because it injects both a type 3 and a type 7 LSA for the default route into the area5.