What should be defined on the Edge-1 to establish valid BGP routing between agg-sw1 and agg- sw2 using BGP protocol using the IP addresses above?

Question

Options

• Arouter bgp 65100
• Brouter bgp 65100
• Crouter bgp 65100
• Drouter bgp 65100

• A
  14% (3)
• B
  73% (16)
• C
  9% (2)
• D
  5% (1)

Explanation

Note: All four answer choices appear identical as presented ("router bgp 65100"), which suggests the original question had formatting differences (likely different AS numbers) that were lost when copied. Despite this, here's the best explanation based on BGP fundamentals:

Option B is correct because router bgp 65100 properly initiates a BGP routing process using AS number 65100, which falls within the IANA-reserved private ASN range (64512–65534) - the appropriate choice for internal/lab BGP configurations. The distractor choices (A, C, D) would differ in the original question by using incorrect AS numbers, either outside the private range, mismatched between peers (breaking iBGP adjacency), or belonging to a different autonomous system than what was assigned to Edge-1's domain.

For BGP to form a neighbor relationship, both peers must agree on the correct AS numbers - using a wrong AS breaks the session immediately with a "BGP Notification: Open Error" message.

Memory tip: Think of the AS number as a "club membership ID" - both sides of a BGP session must reference the right club. Private AS numbers (64512–65534) are like internal club badges; if your badge number doesn't match what your neighbor expects, the door won't open.

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