350-501 Question #432: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. A network engineer is implementing BGP in AS 65101 and AS 65201 R3 sends data traffic to 192.168.1.1/32 via the path R3-R2-R1. The traffic must travel via alternate path R6-R5 for prefix 192.168.1.1/32. Which action must be taken to meet the requirement?

Options

• AApply route-map HIGH-MED out on R2 for neighbor R3
• BApply route-map HIGH-LP in on R3 for neighbor R6
• CApply route-map LOW-MED in on R5 for neighbor R2
• DApply route-map LOW-LP out on R2 for neighbor R3

Explanation

To force R3 to send traffic for 192.168.1.1/32 via R6-R5 instead of R2-R1, a route-map must be applied on R3 to set a higher Local Preference for the prefix received from R6.

Common mistakes.

• A. A high MED makes a route less preferred, and MED is primarily used to influence how other ASes route traffic into your AS, not for internal path selection within an AS or for influencing a neighbor's outbound decision on its own.
• C. Applying a route-map on R5 to influence routes from R2 does not affect R3's path selection for traffic destined to 192.168.1.1/32.
• D. Setting a low Local Preference outbound on R2 for R3 would either have no effect (LP is not propagated eBGP) or would make R3 prefer that path less, which is not the goal of establishing the alternate path.

Concept tested. BGP path selection-Local Preference

Reference. https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-3.html

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