Click the exhibit. AS 65550 owns CIDR block 10.64.0.0/12. Router R3 is advertising Client1 and Client2 networks into BGP. Router R6 advertises the aggregate 10.64.0.0/12 to AS 65541 with…

Question

Options

• AClient1, Client2 and the aggregate.
• BOnly the aggregate.
• COnly Client1 and the aggregate.
• DOnly Client2 and the aggregate.

• A
  3% (1)
• B
  3% (1)
• C
  85% (28)
• D
  9% (3)

Explanation

Option C is correct because BGP aggregate-address with summary-only suppresses only the more-specific routes that fall within the aggregate prefix - Client2's network is within 10.64.0.0/12, so it gets suppressed, while Client1's network lies outside that range and is unaffected, meaning it continues to be advertised normally alongside the aggregate. Option A is wrong because summary-only specifically exists to prevent more-specifics within the aggregate from leaking out. Option B is wrong because summary-only only suppresses routes inside the aggregate; Client1, being outside 10.64.0.0/12, is not a "contributing route" and therefore is never suppressed. Options C and D are mirror images of each other - the key is identifying which client network falls inside versus outside the /12 block. Memory tip: Think of summary-only as a net that catches only the fish inside the aggregate bucket - anything swimming outside the bucket escapes freely.

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