Which of the following statements about routing tools is incorrect? (Multiple choice)

Question

Options

• AThe route control list can be used to match the address of routing information or data packets, and filter routing information or data packets that do not meet the conditions
• BThe prefix list can only be used to filter routing information, not data packets
• CThe community filter is a tool used to match the community attributes in BGP routing information. It can filter BGP routes independently according to the community attributes of BGP routes
• DThe path-filter is a tool used to match the attribute in BGP routing information. It can filter BGP routes independently according to the AS Path attribute of BGP routing

• A
  10% (2)
• B
  10% (2)
• C
  80% (16)

Explanation

Options C and D are the incorrect statements because both the community filter and path-filter are matching tools, not independent filtering tools - they must be referenced inside a route-policy (route-map) to actually filter BGP routes. Saying they "can filter BGP routes independently" is the error in both C and D.

Why A is correct (not a distractor): Route control lists (ACLs) are versatile - they can match both routing information (used in route policies) and data packets (used in traffic filtering), so statement A accurately describes their dual use.

Why B is correct (not a distractor): Prefix lists operate purely on IP prefix/length matching within routing protocols and cannot be applied to data-plane traffic, making statement B accurately limited.

Memory tip: Think of community filters and path-filters as "lenses, not levers" - they help you see (match) specific BGP attributes, but you still need a route-policy as the actual lever to take action. If a tool needs a route-policy to do anything useful, it cannot filter "independently."

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