Which of the following is considered a best practice for BGP address planning?

Question

Options

• AAdvertising external networks into IGP.
• BUsing system addresses for setting up iBGP sessions.
• CExporting the networks associated with the external links of eBGP peers into BGP.
• DOptimizing BGP route table by exporting IGP routes into BGP.

• A
  3% (1)
• B
  89% (34)
• C
  3% (1)
• D
  5% (2)

Explanation

Using system (loopback) addresses for iBGP sessions is correct because loopback interfaces are always up as long as the router itself is operational - unlike physical interfaces that can fail. This makes iBGP sessions far more stable and resilient, since a session tied to a loopback can survive a single link failure as long as another path to the router exists.

Why the distractors are wrong:

• A is incorrect - advertising external routes into an IGP (like OSPF/IS-IS) bloats the IGP table with routes it was never designed to scale for; external reachability belongs in BGP.
• C is incorrect - exporting the eBGP peer's external link networks into BGP is unnecessary and can cause routing anomalies; you advertise your own prefixes, not your peer's link addresses.
• D is incorrect - redistributing IGP routes into BGP risks route leakage, instability, and unnecessarily inflates the BGP table with internal infrastructure routes.

Memory tip: Think "Loop for longevity" - loopback addresses outlive any single link, so tying iBGP to them keeps your sessions alive through failures.

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