R2 and R3 advertise a default route into Area 1.Based on the configurations in the exhibit, which statement is true? (Choose two.)
A.
Traffic from R1 to internal OSPF destinations in Area 0 will always transit R4.
B.
Traffic from R1 to internal OSPF destinations in Area 0 will always transit R2.
C.
Traffic from R1 to external OSPF destinations in Area 0 will always transit R2.
D.
Traffic from R1 to external OSPF destinations in Area 0 will always transit R4.
I think there is a typo in the question. It should be “R2 and R4 advertise a default route into….”.
Hi I’m quite confuse with the answer.
I thought the option stub default-metric 5 “no-summaries” allow only internal routes and default route advertisements into the area, i.e. NO external routes.
If this is correct then the correct answer should be D?
Now for internal routes, wouldn’t it just take R2 which have a lower default metric, so answer B is also the right one.
So wouldn’t the answer be B and D?
Can someone please share their thoughts?
I also think k B and D should be the right answer… I would be glad if anybody can explain it??
I think answers A and C are correct. R1 sees an LSA type 3 summary flooded by R4 describing the internal destinations in area 0. Therefore R1 will always route via R4 to reach area 0 internal destinations.
Both stub and stub no-summaries do not flood external summaries to other areas. So, R1 will see a default route from both R2 and R4 to reach destinations external to area 0. As the igp metric to reach both ABR’s equal, It will choose the one with the lowest advertised metric, which is R2.
According to lab configuration i have answers A and C.
In my lab external route 50.0.1.0/24 is injected into ospf. IP 10.1.1.6 is interface on R3 between R3 and R5.
10.10.1.1 is interface on ABR R2 and 10.10.1.5 is interface on ABR R4.
Based on trace I get following results from R1:
root@R1> traceroute 50.0.1.1 (external route
traceroute to 50.0.1.1 (50.0.1.1), 30 hops max, 40 byte packets
1 10.10.1.1 (10.10.1.1) 3.155 ms 1.377 ms 1.018 ms
2 50.0.1.1 (50.0.1.1) 2524.935 ms 3.616 ms 3.034 ms
root@R1> traceroute 10.1.1.6 (interface between R3 and R4)
traceroute to 10.1.1.6 (10.1.1.6), 30 hops max, 40 byte packets
1 10.10.1.5 (10.10.1.5) 2.371 ms 1.216 ms 1.406 ms
2 10.1.1.10 (10.1.1.10) 1.539 ms 2.811 ms 3.193 ms
3 10.1.1.6 (10.1.1.6) 55.041 ms 244.173 ms 3.653 ms
Regards,