Please match the following BGP-recognized community attribute names with their corresponding functions.

Question

Options

• AInternet maps to 'After the device receives a route with this attribute, it can send the route to any BGP peer.'; No_Advertise maps to 'After the device receives a route with this attribute, it will not send the route to any BGP peer.'; No_Export maps to 'After the device receives a route with this attribute, it will not send the route outside the AS.'; No_Export_subconfed maps to 'After the device receives a route with this attribute, it will not send the route outside the AS, nor will it send to any sub-ASs in the AS.'
• BNot provided in the source.
• CNot provided in the source.
• DNot provided in the source.

• A
  79% (26)
• B
  12% (4)
• C
  6% (2)
• D
  3% (1)

Explanation

Option A is correct because it accurately maps all four BGP well-known community attributes to their defined behaviors as specified in RFC 1997. The four attributes form a spectrum from completely open (Internet) to completely closed (No_Advertise), with No_Export and No_Export_subconfed occupying intermediate positions that restrict propagation at the AS and sub-AS boundaries respectively. Options B, C, and D are marked as "not provided in the source," meaning they offer no valid matching at all and can be eliminated immediately.

To keep the four straight, think of them as levels of increasing restriction: Internet imposes no restriction and allows the route to go anywhere; No_Export stops the route at the AS boundary but allows it to circulate within the AS including its sub-confederations; No_Export_subconfed is stricter and confines the route to the local sub-AS, blocking it from even crossing to other sub-ASes within the same confederation; and No_Advertise is the most restrictive, preventing the route from being shared with any BGP peer whatsoever.

Memory tip: Picture a series of fences. Internet has no fence. No_Export builds a fence around the entire AS. No_Export_subconfed builds a fence around just the local sub-AS inside that larger AS. No_Advertise locks the route in a box so it goes nowhere at all.

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