Click the Exhibit button. In the exhibit, R1 and R2 have a static default route configured that
points toward the provider. Both routers redistribute the default route into OSPF. R2 is the
preferred gateway to reach the provider. R1 is the backup gateway. All link metrics are
equal. Which two steps ensure that traffic to the provider flows through R2 while the network
is working properly? (Choose two.)
A.
Redistribute the default route as a Type 2 external route on router R1 and a Type 1
external route on router R2.
B.
Modify the preference value of the default route on router R1 so that it is less preferred
than OSPF external routes.
C.
Redistribute the default route as a Type 1 external route on router R1 and a Type 2
external route on router R2.
D.
Modify the preference value of the default route on router R2 so that it is more preferred
than OSPF external routes.
Option B is quite simple.
Regarding option A, at first glace, it seems type 2 on R1 means only external cost is added and type 1 on R2 means internal (upto ASBR) and external both cost are added so initially it seems type 1 should be on R1 to get R2 path preferred.
But theories say, We only compare cost between routes of the same type:
10a Intra-Area
10b Inter-Area
150a Type 1 External
150b Type 2 External
But here it’s different type (type 1 and type 2), so always route selection happens in in sequence by intra-area, inter-area, type 1 external and then type 2 external.
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Reference from the site: http://mdm.me/junos-ospf-external-type-1-vs-type-2-explained/
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