Exam 350-501 topic 1 question 271 discussion

Hi, in my understanding, answer B is correct: Routes are redistributed in OSPF as either type 1 (E1) routes or type 2 (E2) routes, with type 2 being the default. A type 1 route has a metric that is the sum of the internal OSPF cost and the external redistributed cost. A type 2 route has a metric equal only to the redistributed cost. If routes are redistributed into OSPF as type 2 then every router in the OSPF domain will see the same cost to reach the external networks. If routes are redistributed into OSPF as type 1, then the cost to reach the external networks could vary from router to router. The order of preference for OSPF as per RFC 2328 is : intra-area routes, O interarea routes, O IA external routes type 1, O E1 external routes type 2, O E2 This rule of preference cannot be changed. I hope this helps. Good luck.

A is wrong because PE1 is already receiving a default route Metric Type 1 cost 50. If we inject another default route with a metric type 2 (as answer A suggests) that route will not be used even if the cost is lower and the traffic will go to R4.

I guess both answers (A and B) Will work well. “A” seems to be “cleaner” since it will work even though you raise cost between P2 and P4 and P4 will be always preferred. So A is ok for me.

1) E1 over E2. 2) The option 'always' is not needed in this scenario.

- If routes are redistributed into OSPF as type 2 then every router in the OSPF domain will see the same cost to reach the external networks. Then In such case, option B becomes more viable as the question asks Router P4 to become the primary Internet gateway for the network. And if, - If routes are redistributed into OSPF as type 1, then the cost to reach the external networks could vary from router to router. In such a case, the objective of the ask here would fail as each Router in the OSPF domain would see a different cost to reach the external networks.

As per me, answer should be : B - If routes are redistributed into OSPF as type 2 then every router in the OSPF domain will see the same cost to reach the external networks. Then In such case, option B becomes more viable as the question asks Router P4 to become the primary Internet gateway for the network. And if, - If routes are redistributed into OSPF as type 1, then the cost to reach the external networks could vary from router to router. In such a case, the objective of the ask here would fail as each Router in the OSPF domain would see a different cost to reach the external networks.

Hi, in general you are right, but the question states P4 to become the "primary" gateway. With this condition I think A is the right answer, coz this way the route of P5 will only become best when P4 does not advertise the default route any more.

E1 better than E2 and "always" is not good here, that would advertise the default even when the Internet default route is down.

ospfv3 ? where is ipv6 ?

Definetely type 1.

type 1 versus type 2 so B is good!