Preventing Type 5 LSA and OSPF Adjacency
Question
A network engineer is provisioning a wireline IP customer so that the interface IPv4 address is announced into OSPF.
The engineer wants to prevent a new type 5 LSA from being originated and the customer from becoming OSPF adjacent.
Which two actions accomplish this goal? (Choose two.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.CE.
To prevent a new type 5 LSA from being originated and the customer from becoming OSPF adjacent, two actions can be taken:
Redistribute connected routes into OSPF, but allow only the specific customer prefix using a route map: This can be achieved by configuring a route-map that permits only the specific customer prefix and denying everything else. Then, redistribute the connected routes into OSPF using this route-map. This will ensure that only the desired customer prefix is announced into OSPF and other prefixes are not. As a result, no new type 5 LSA will be originated, and the customer will not become OSPF adjacent.
Configure OSPF passive on the customer interface: This can be achieved by configuring the OSPF passive interface command on the customer interface. This will prevent the interface from sending OSPF hello messages, and hence, no adjacency will be formed. As a result, no new type 5 LSA will be originated, and the customer will not become OSPF adjacent.
The other options do not accomplish the goal of preventing a new type 5 LSA from being originated and the customer from becoming OSPF adjacent.
Option A, adding the customer IP prefix to the OSPF process by using the area range command will cause the customer to become OSPF adjacent, which is the opposite of what is desired.
Option C, adding the customer interface to the OSPF process will also cause the customer to become OSPF adjacent, which is the opposite of what is desired.
Option D, configuring OSPF cleartext authentication on the customer interface, has no effect on preventing a new type 5 LSA from being originated and the customer from becoming OSPF adjacent.
Therefore, the correct answers are B and E.
