Refer to the exhibit. Routers CE1 and CE2 are in AS 65530. which is multihomed for Internet access. An engineer expects inbound traffic to AS 65530 to arrive from PE1. But it is coming from PE2…

Question

Exhibit

Options

• AOn router CE2, configure inbound routes from PE2 to CE2 with a local-preference value of 50 or
• BConfigure router CE1 to prepend the AS path to routes it receives from PE1.
• CSet the local-preference value on router CE1 to 100 or greater
• DOn router PE1, change the origin for routes that are redistributed from CE1 to CE2.

• A
  13% (5)
• B
  28% (11)
• C
  50% (20)
• D
  10% (4)

Explanation

Setting local preference to 100 or greater on CE1 for routes learned from PE1 makes those routes preferred across all routers in AS 65530 via iBGP - a higher local preference wins the BGP path selection process, so if CE1's LP for PE1 routes is currently below the default of 100, traffic is biased toward PE2. Correcting CE1's local preference to 100+ restores PE1 as the preferred path, which directly addresses the root cause shown in the exhibit.

Why the distractors are wrong:

• A sets local preference to 50 on CE2 (lowering PE2's preference), which could work directionally but doesn't fix the actual deficiency on CE1 - it treats the symptom on the wrong router.
• B has CE1 prepend AS path on routes it receives from PE1, which is mechanically incorrect (prepending applies to routes you advertise) and would make PE1 look less attractive to external peers, worsening the problem.
• D modifying the origin attribute on PE1 is irrelevant - origin (IGP/EGP/incomplete) has no bearing on local preference decisions, and CE1-to-CE2 path selection happens via iBGP local preference, not origin.

Memory tip: Think "Local pref controls traffic Leaving your AS" - higher wins, default is 100. If traffic is exiting the wrong router, check local preference on the router connected to your preferred exit. AS path prepending influences inbound traffic (external routers' decisions), while local preference influences outbound (your AS's decision).

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