Refer to the exhibit. The Internet traffic should always prefer Site-A ISP-1 if the link and BGP connection are up; otherwise, all Internet traffic should go to ISP-2.
Redistribution is configured between BGP and OSPF routing protocols, and it is not working as expected.
What action resolves the issue?
OSPF prefers external routes of type E1 over those of type E2, regardless of the metric. By setting the metric-type to 1 at Site-A RTR1 and metric-type to 2 at Site-B RTR2, Site-A's route will always be preferred when available. This ensures that Internet traffic prefers Site-A's ISP-1 connection as long as it is up, achieving the desired routing behavior.
OSPF prefers E1 over E2
The correct answer is: C
Can you explain why? I believe setting OSPF cost to 100 at SITE1 would select that site to be the exit path according to BGP Best PAs... Again, I am not sure. Just looking for an explanation.
C is likely a better answer because modifying cost could require manually modifying several interfaces to get the intended effect... whereas just simply modifying external type during redistribution immediately allows all routers to prefer external type1 routes over external type2.
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.
User piojo is correct. Answer is C. E1 over E2 routes all day, regardless of cost.
As already explained. Type 1 over type 2, and to add to the explanation. Remember that an external route redistributed into OSPF is by default type 2, this is why the initial design was not working as intended. The default route from ISP1 needed to be defined as type 1
https://networklessons.com/ospf/ospf-path-selection-explained OSPF will first look at the “type of path” to make a decision and, secondly look at the metric (cost). type of path - path selection order: O > O IA > N1 > E1 > N2 > E2
C is correct
Before it is redistributed you need the IGP to prefer a path, in this case changing the ospf cost will allow one path to be preferred over the other
setting the costs 100 and 200 and not calculating it will make sit-A preferred immediately on the routers regardless of adding bandwidth to the destination D is correct