Which of the following descriptions about BGP route equal-cost load sharing are correct? (Multiple choice) A. By default, the device will only perform load balancing on routes with the same AS_Path…

Question

Options

• ABy default, the device will only perform load balancing on routes with the same AS_Path length.
• BAfter the BGP load balancing function is enabled on the device, only multiple BGP routes that meet the conditions will become equal-cost routes for load balancing.
• CIBGP and EBGP routes to the same destination on the public network cannot form load balancing.
• DAfter BGP load balancing is configured, the device will advertise multiple load balancing routes to peers.

• A
  21% (14)
• B
  79% (54)

Explanation

B, C, and D are correct because they accurately describe how BGP equal-cost load balancing (ECMP) works in practice.

B is correct because enabling load balancing (e.g., via maximum load-balancing) does not automatically make all BGP routes eligible - only routes that satisfy specific equal-cost conditions (identical AS_Path, MED, Origin, etc.) are installed as equal-cost paths in the routing table.

C is correct because IBGP and EBGP routes cannot be mixed for load balancing, even to the same destination - EBGP routes are always preferred over IBGP routes during path selection, so they belong to different "tiers" and cannot form an equal-cost group together.

D is correct because once BGP load balancing is configured, the device will advertise the multiple qualifying load-balancing routes to its peers, allowing downstream devices to also benefit from the multipath information.

A is the distractor - it falsely implies BGP performs load balancing by default. In reality, BGP selects only a single best path by default; load balancing must be explicitly configured, and same AS_Path length is a condition for EBGP load balancing only once enabled, not a default behavior.

Memory tip: BGP is "one best path" by default - you must enable sharing (B), it won't cross the IBGP/EBGP boundary (C), and once enabled it does share routes with peers (D). A trips you up by sneaking in the word "default."

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