Please match the name of the BGP recognized community attribute with its function.

Question

Options

• ANo Advertise: After the device receives a route with this attribute, it will not send the route to any BGP peer; No Export: After the device receives a route with this attribute, it will not send the route map outside AS; Internet: As a backup of the designated port, it provides another backup path from the root bridge to the corresponding network segment.; No Export Subconfed: After the device receives a route with this attribute, it will not advertise this route to other sub-ASs in the AS.
• B
• C
• D

• A
  79% (19)
• B
  4% (1)
• C
  13% (3)
• D
  4% (1)

Explanation

Option A is correct because it is the only choice that contains any content - options B, C, and D are empty, making A correct by elimination, and the core definitions it provides for No Advertise, No Export, and No Export Subconfed accurately reflect RFC 1997 BGP community behavior. No Advertise means the receiving router suppresses the route from all BGP peers, internal or external. No Export means the route stays within the AS and is not sent to any external BGP neighbor. No Export Subconfed further limits propagation within a BGP confederation, blocking the route from leaving the local sub-AS. Note that the description given for the Internet community in option A ("backup of the designated port... root bridge") is STP language mistakenly inserted here; the actual BGP Internet community means a route carries no restriction and may be advertised to any peer, which is the opposite of the other three communities.

Memory tip: Think of the four communities as a dial from least to most restrictive - Internet (advertise anywhere), No Export Subconfed (stop at sub-AS boundary), No Export (stop at AS boundary), No Advertise (stop everywhere). Each name literally describes where the advertisement stops.

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