Which of the following descriptions about Policy-Based-Routing and Routing-Policy are correct? (Multiple choice)

Question

Options

• AThe deployment of the routing policy is based on the forwarding plane and will not affect the routing table entries
• BAfter the device receives the message, the policy routing will first search for the policy for matching and forwarding. If the match fails, it will search the routing table for forwarding
• CRouting policies can only be formulated based on source addresses
• DPolicy routing can formulate policies based on parameters such as source and destination IP addresses, protocol types, and packet sizes

• A
  11% (2)
• B
  84% (16)
• C
  5% (1)

Explanation

B and D are correct because Policy-Based Routing (PBR) operates at the forwarding plane and intercepts packets before the routing table is consulted - if a packet matches a PBR policy, it's forwarded per that policy; otherwise, normal routing table lookup takes over (B). PBR is also highly flexible in its match criteria, supporting source/destination IP, protocol type, packet size, and more (D).

A is wrong because it misdescribes which feature works at the forwarding plane - PBR operates there, but Routing Policy operates at the control plane and directly does affect routing table entries (e.g., filtering or modifying routes during import/export).

C is wrong because Routing Policies can be formulated based on many attributes beyond source addresses - including destination prefix, AS path, community values, MED, and next-hop.

Memory tip: Use the acronym "PBR = Packet Before Routing" - Policy-Based Routing intercepts the packet first (forwarding plane, flexible match criteria), while Routing Policy controls the routes themselves (control plane, affects the routing table). This distinction cleanly separates B/D from the distractors A and C.

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