Click the exhibit. Router R2 receives a route to 192.168.1.0/27 from router R4, and sets the local preference to 110. Router R1 receives a route to 192.168.1.0/27 from router R3, and sets the local…

Question

Options

• AR1-R3-R8
• BR1-R2-R4-R8
• CR1-R3-R4-R8
• DR1-R2-R3-R8

• A
  4% (1)
• B
  77% (20)
• C
  8% (2)
• D
  12% (3)

Explanation

Option B is correct because BGP local preference is propagated to all routers in the AS via iBGP, so R1 learns about both exit paths: via R3 (local-pref 80) and via R2 (local-pref 110). Since higher local preference always wins, R1 selects R2 as the best exit, then traffic follows R2's learned path to R4 and onward to R8. Option A (R1-R3-R8) is wrong because it would require the lower local preference (80 via R3) to win, which violates BGP path selection rules. Option C (R1-R3-R4-R8) is topologically inconsistent - R4 peers with R2, not R3, so traffic through R3 would not reach R4 directly. Option D (R1-R2-R3-R8) is wrong because BGP would never loop traffic back through R3 after already exiting via R2.

Memory tip: Think of local preference as a "loyalty score" - the higher the score, the more the whole AS "votes" for that exit door. Because iBGP floods the local-pref value everywhere, even R1 (which learned the route via R3) ends up choosing R2's door since 110 beats 80.

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