Which of the following tools cannot be used for route filtering?

Question

Options

• ARoute-policy
• BPrefix-policy filter
• Cip-prefix
• DACL

• A
  6% (3)
• B
  12% (6)
• C
  2% (1)
• D
  80% (39)

Explanation

ACL (Access Control List) is designed for packet/traffic filtering at Layers 3–4, controlling which data packets are permitted or denied through an interface - not for filtering routing protocol advertisements or prefixes. Route-policy (A) is a direct route filtering and attribute manipulation tool used in BGP and other protocols. Ip-prefix lists (C) match specific IP networks and are commonly referenced by route-policies and filter-policies to define which prefixes are permitted or denied. Prefix-policy filter / filter-policy (B) is applied within IGP protocols (like OSPF, IS-IS, RIP) to control which routes are imported or exported between routing tables.

Memory tip: Think "ACL filters packets flowing through the router; route tools filter routes stored in the routing table." If a tool name contains route, prefix, or filter-policy, it belongs to the route filtering family - ACL does not.

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