350-401 Question #144: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An engineer must ensure that all traffic leaving AS 200 will choose Link 2 as the exit point. Assuming that all BGP neighbor relationships have been formed and that the attributes have not been changed on any of the routers, which configuration accomplish task?

Options

• AR4(config-router)bgp default local-preference 200
• BR3(config-router)neighbor 10.1.1.1 weight 200
• CR3(config-router)bgp default local-preference 200
• DR4(config-router)nighbor 10.2.2.2 weight 200

Explanation

BGP Local Preference & Weight Explanation

Option A is correct because bgp default local-preference 200 configured on R4 raises the local preference for routes learned via Link 2 (R4's exit point) above the default value of 100. Since local preference is shared across the entire AS, all routers in AS 200 will prefer R4's path, ensuring all outbound traffic exits through Link 2.

Why the distractors are wrong:

• Option B is wrong because weight is a Cisco-proprietary attribute that is local to a single router only - setting weight on R3 would only influence R3's routing decisions, not the entire AS.
• Option C is wrong because configuring local preference on R3 would advertise a higher preference for routes via Link 1 (R3's exit), which is the opposite of the desired outcome - traffic would prefer R3, not R4.
• Option D is wrong for the same reason as B - weight is not propagated to other BGP routers within the AS, so R4's weight setting would not influence R3's path selection.

🧠 Memory Tip: Think "L for Local-preference = aSs-wide" vs. "W for Weight = one router Only" - Local preference influences the whole AS, while Weight is router-specific. When you need AS-wide influence, always reach for Local Preference!

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