350-401 Question 198
Single answerYou are tasked with configuring a highly available gateway for a set of VLANs in your enterprise network. You decide to implement HSRP on two routers, R1 and R2, with R1 as the active router. After configuring the HSRP group, you notice that both R1 and R2 are claiming to be the active router. What is the most likely cause of this issue?
- A
The HSRP priority on R1 and R2 is incorrectly set to the same value.
- B
The HSRP group number is mismatched between R1 and R2.
- C
Preemption is not enabled on either R1 or R2.
- D
The HSRP authentication configuration is mismatched between R1 and R2.
Show answer and explanation
Correct answer: D
Explanation
When an HSRP authentication configuration is mismatched between two routers, they fail to recognize each other as part of the same HSRP group. As a result, both routers independently assume the active role, leading to a conflict. Ensuring that the authentication parameters (e.g., key strings) match is crucial for HSRP operation.
- A. Incorrect.
If the HSRP priority is the same on both routers, the router with the higher IP address becomes the active router by default. This would not cause both routers to claim the active role unless there is another configuration issue.
- B. Incorrect.
A mismatched HSRP group number would result in the routers not forming an HSRP relationship at all. They would not recognize each other as part of the same group.
- C. Incorrect.
Preemption determines whether a higher-priority router can take over the active role from a lower-priority router. However, it does not cause both routers to claim the active role simultaneously.
- D. Correct.
HSRP authentication is used to ensure that only routers with matching authentication configurations participate in the same HSRP group. A mismatch in authentication can result in both routers acting independently, leading to both claiming the active role.