Which of the following descriptions about BGP routing are correct? (Multiple choice)

Question

Options

• ASimilar to ordinary IGP, BGP itself also calculates and generates routes
• BBGP supports policies that affect route or packet routes
• CBGP can aggregate based on existing routing entries
• DBGP supports to extend supports injecting direct routes into the BGP routing table

• A
  18% (7)
• B
  82% (31)

Explanation

B, C, and D are correct because BGP is a policy-driven path-vector protocol - it does not compute shortest paths itself, but instead selects routes based on attributes and administrator-defined policies (B). BGP supports route aggregation (summarization) by combining more-specific prefixes into a single advertisement, provided those components exist in the routing table (C). BGP also allows redistribution of directly connected routes into the BGP table via network statements or redistribution, making (D) correct.

Option A is wrong because BGP does not calculate routes using its own algorithm the way IGPs (OSPF, IS-IS) do with SPF or DUAL. BGP is a path-vector protocol that selects among advertised paths using attributes (AS_PATH, LOCAL_PREF, MED, etc.) - it relies on IGPs to resolve next-hops, not to generate routes itself.

Memory tip: Think of BGP as a policy manager, not a route calculator. The acronym PAD helps: Policies (B), Aggregation (C), Direct-route injection (D) - all things BGP manages. IGPs do the math; BGP does the politics.

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