Exam 400-007 topic 1 question 205 discussion

C https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/4170-ospfprocesses.html

I think answer is C. Use route maps to tag routes to be redistributed by the Autonomous System Boundary Router (ASBR) and check and filter those tags during redistribution to prevent the same routes from returning to the network again and avoid routing loops This avoids routing loops. This effectively reduces the risk of loops when redistributing routes between different OSPF networks.

Answer is A: Redistribute routes as external type 2 routes: When redistributing routes between OSPF and other routing protocols or between different OSPF areas, it is crucial to manage how external routes are advertised within the OSPF network. OSPF uses two types of external routes: Type 1 (E1) and Type 2 (E2). Type 2 is commonly used for redistribution because it only considers the cost to reach the ASBR (Autonomous System Boundary Router) and does not take into account the internal cost of the path to the ASBR. This approach helps in preventing routing loops and ensures that external routes are properly managed and loop-free.

To fulfill the requirements of mutually redistributing two OSPF networks at multiple locations while avoiding the creation of routing loops, you can use route maps on Autonomous System Boundary Routers (ASBRs) to filter routes with tags so they are not redistributed. By applying route maps on the ASBRs, you can selectively filter and control which routes are redistributed between the OSPF networks. By tagging the routes and using route maps to filter based on these tags, you can prevent routing loops from occurring. This approach allows you to control the redistribution of routes and ensure end-to-end connectivity to all of the company's networks while avoiding any potential routing issues.

To avoid routing loops you need to tag packets

C. https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/4170-ospfprocesses.html

Redistributing routes from one OSPF network to another can create routing loops if not carefully planned. A virtual link can be used to connect two non-backbone areas through the backbone area without having to physically connect them. This would ensure end-to-end connectivity while avoiding the creation of routing loops.

C is correct

C ans is correct