300-320 Question #574: Real Exam Question with Answer & Explanation

The correct answer is C: Filter routes to receive only routes with AS of branches. A slow WAN edge router cannot efficiently process a full BGP routing table. The solution is to use AS path filtering to reduce the BGP table to only branch-relevant routes. Option C ('Filter routes to receive only routes with AS of branches') uses an AS path access list to accept

Question

A slow performance router installed on Wan Edge to ensure connectivity with branches, how to configure BGP? (choose two)

Options

ASet maximum path number
BConfigure iBGP
CFilter routes to receive only routes with AS of branches
DFilter routes to get more specific routes
EFilter routes to get routes including AS of branches

Explanation

A slow WAN edge router cannot efficiently process a full BGP routing table. The solution is to use AS path filtering to reduce the BGP table to only branch-relevant routes. Option C ('Filter routes to receive only routes with AS of branches') uses an AS path access list to accept inbound routes whose AS path contains only the branch AS numbers - eliminating irrelevant internet or other peer routes. Option E ('Filter routes to get routes including AS of branches') complements this by ensuring routes that transit through branch AS numbers are also accepted, covering scenarios where branch routes are advertised through intermediate ASes. Together, these two filters drastically reduce the BGP table size on the slow router, improving performance while maintaining branch reachability. Option A (maximum-path) enables load balancing but does not reduce table size. Option B (iBGP) is incorrect context since WAN edge to branch is typically eBGP. Option D (more specific routes) would increase table size, worsening performance.

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