Click the exhibit button.
In the topology shown, router R1 is an ASBR configured to export external routes to OSPF. How many type 4 LSAs will be present in the network?
4A0-101 Exam QuestionsBrowse all questions from this exam
4A0-101 Exam - Question 3
Show AnswerHide Answer
Correct Answer: AD
In the provided network topology, router R1 is an ASBR (Autonomous System Boundary Router) that exports external routes to OSPF. Type 4 LSAs (ASBR Summary LSAs) are generated by ABRs (Area Border Routers) to inform other routers within the OSPF domain about the presence of an ASBR and how to reach it. Since there is only one ASBR (R1) in this network, only one Type 4 LSA will be generated by the ABR (R2) to summarize the routes to the ASBR. Therefore, there will be one Type 4 LSA present in the network.
Discussion
3 commentsKri8orOption: D
Jul 9, 2019LSA Type 4 is a ASBR Summary LSA, and it's generated by the ABR. It is flooded from area 0 into a non-transit area and vice versa - "from" is the key word here. Basically it represents the ABR's reachability to ASBRs. It tell that he - the ABR - knows how to reach netwroks outside the OSPF domain via ASBR. So, the ASBR will generate a type 5 into are 0 - Not a 7. Type 7 LSAs are generated if we have a NSSA. ASBR generates a 5 informing its area that he has routes that were redistributed into OSPF. The ABR in turn, once he receives type 5 LSAs with its origin in the ASBR, he will know that those are external to the OSPF Domain, and will tell the adjacent area that he knows a way outside the OSPF domain via ASBR. He wont share the networks because there is no need to overload the adjacent area with unnecessary information. They just need to know how to get out.
flamengo
May 19, 2019Hi guys. Someone will explain is question?
qtygbapjpesdayazko
Nov 27, 2022Correct ASBR will generate a type 5 into are 0