Which of the following is NOT a goal of BGP routing policies?

Question

Options

• ATo protect external networks from instability.
• BTo communicate the architecture of an AS to external ASs.
• CTo protect the local AS and other external ASs from bad NLRI.
• DTo optimize ingress and egress traffic patterns to best serve the users of the AS.

• A
  15% (9)
• B
  77% (47)
• C
  3% (2)
• D
  5% (3)

Explanation

B is correct because BGP routing policies are not designed to advertise or communicate the internal architecture of an Autonomous System (AS) - that information is intentionally kept private. In fact, a key principle of inter-domain routing is that ASes are treated as opaque entities; only reachability information (NLRI) is shared, not internal topology.

Why the distractors are wrong:

• A is a real BGP goal - route filtering and dampening protect neighbors from flapping routes and instability originating inside your AS.
• C is a real BGP goal - filtering bad or bogus NLRI (e.g., invalid prefixes, private address space) prevents propagation of routing errors or hijacks.
• D is a real BGP goal - policies like MED, local preference, and AS path prepending are used precisely to shape how traffic enters and exits the AS for performance and cost reasons.

Memory tip: Think of BGP policies as a bouncer, not a tour guide - they control what gets in and out, protect the neighborhood, and direct traffic flow, but they never reveal the floor plan of the building. If an answer involves exposing internal structure, it's outside BGP policy's scope.

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