Which BGP feature causes to replace the AS number of originating router with the AS number of the sending router?

Question

Options

• Aroute reflectors
• Broute dampening
• Cconfederations
• DAS override

• A
  3% (1)
• C
  3% (1)
• D
  93% (28)

Explanation

AS Override is the correct answer because it is specifically designed to replace the originating router's AS number in the AS_PATH attribute with the AS number of the sending (provider) router - typically used when a customer has the same AS number at multiple sites connected to the same service provider, preventing BGP's normal loop-detection mechanism from dropping the routes.

Route reflectors (A) are an IBGP scaling solution that allow a single router to re-advertise routes to IBGP peers without a full mesh; they do not modify AS numbers in the AS_PATH. Route dampening (B) suppresses unstable, frequently flapping routes using a penalty system - it has nothing to do with AS number substitution. Confederations (C) split a large AS into smaller sub-ASes to reduce IBGP complexity; while confederation sub-AS numbers are stripped before leaving the confederation boundary, this is not the same as replacing the originating AS number with the sender's AS number on a per-neighbor basis.

Memory tip: Think of the word "override" literally - the sending router overrides (overwrites) the customer's AS number with its own before advertising the route onward. If you see "replace AS number," think AS override.

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