Refer to the exhibit.
 
ROUTE Enterprises has many stub networks in their enterprise network, such as router B and its associated network. EIGRP is to be implemented on router A so that neither the prefix for the S/0/0/0 interface nor the prefixes from router B appear in the routing tables for the router in the enterprise network. Which action will accomplish this goal?

A. Declare router B a stub router using the eigrp stub command.

B. Use the passive-interface command for interface Serial0/0/0.

C. Use a mask with the network command to exclude interface Serial0/0/0.










 

Suggested Answer: D. Implement a distribute list to exclude the link prefix from the routing updates.

Explanation -
If we declare router B a stub router then the routers in Enterprise Network still learn about the network for S0/0/0 interface and the network behind router B.
If we use the passive-interface command on s0/0/0 interface then router A & B can not become neighbor because they don`t exchange hello messages -> A can not send traffic to the network behind B .
Theoretically, we can use a distribute list to exclude both the link prefix and the prefix from router B but it is not efficient because:
+ We have many stub networks so we will need a long distribute list. + We declare networks in stub routers (like router B) while filter them out at router A -> it is a waste.
Not totally sure about answer C because if we use a mask with the network command to exclude interface Serial0/0/0 then router A and B can not become neighbors and the situation is same as answer B. But from many discussions about this question, maybe C is the best answer.

This question is in 300-101 Cisco Implementing Cisco IP Routing (ROUTE) Exam
For getting Cisco Certified Network Professional (CCNP) Routing and Switching Certificate




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