You have configured an OSPF stub area. The routes in the stub area require external reachability.
Which statement explains how OSPF meets this requirement?
A.
The ABR will generate a 0.0.0.0/0 martian route in the area.
B.
The ABR will flood Type 5 LSAs into the area.
C.
The ABR will flood Type 7 LSAs into the area.
D.
The ABR will generate a 0.0.0.0/0 default route in the area.
Explanation:
Reachability for routes external to OSPF is achieved via a 0/0 default route injected by the ABR.
https://forums.juniper.net/jnet/attachments/jnet/Learning/58/2/AJNR_Module02_OSPF-Stub_5-1-
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D correct
set protocols ospf area ## stub default-metric ##
https://www.juniper.net/documentation/en_US/junos/topics/concept/ospf-stub-areas-overview.html
Note: You must explicitly configure the ABR to generate a default route when attached to a stub or not-so-stubby-area (NSSA).
To inject a default route with a specified metric value into the area, you must configure the default-metric option and specify a metric value.
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Option D, Final answer.
Stub Areas
Stub areas are areas through which or into which AS external advertisements are not flooded. You might want to create stub areas when much of the topological database consists of AS external advertisements. Doing so reduces the size of the topological databases and therefore the amount of memory required on the internal routers in the stub area.
Routing devices within a stub area rely on the default routes originated by the area’s ABR to reach external AS destinations. You must configure the default-metric option on the ABR before it advertises a default route.
Once configured, the ABR advertises a default route in place of the external routes that are not being advertised within the stub area, so that routing devices in the stub area can reach destinations outside the area.
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