In BGP routing rules, which of the following options is used to determine the priority of the Origin attribute?

Question

Options

• AIncomplete > EGP >BGP
• BBGP > EGP > Incomplete
• CEGP > Incomplete > BGP
• DEGP > Incomplete <EGP

• A
  9% (3)
• B
  82% (28)
• C
  6% (2)
• D
  3% (1)

Explanation

Option B is correct because BGP's Origin attribute has a defined preference hierarchy where routes with an IGP origin (labeled "BGP" in many vendor contexts, meaning the route was injected via a network statement or IGP) are preferred, followed by routes learned via the older EGP protocol, and finally Incomplete routes, which result from redistribution into BGP and have the least-known origin. Option A reverses this order entirely, incorrectly placing Incomplete as the most preferred, which would mean the least-certain origins win out over well-known ones. Option C incorrectly elevates EGP above both others and places BGP-originated routes at the lowest priority, which contradicts the standard. Option D is malformed, referencing EGP twice and using an inconsistent comparison operator, making it meaningless as a ranking.

Memory tip: Think of it as a trust hierarchy - you trust what your own network told BGP most (BGP/IGP origin), then what a neighboring EGP told you, and least of all an incomplete or redistributed route where the true origin is uncertain. "Best to Worst: BGP, EGP, ?".

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