Which two practices will avoid Cisco Express Forwarding polarization?(Choose two.)

Question

Options

• AThe core layer should use default Layer 3 hash information.
• BThe core layer should use default Layer 4 hash information.
• CThe distribution layer should use default Layer 3 hash information.
• DThe distribution layer should use default Layer 4 hash information.
• EThe core layer should use Layer 3 and Layer 4 information as input to the Cisco Expressing
• FThe distribution layer should use Layer 3 and Layer 4 information as input into the Cisco

• A
  60% (18)
• B
  3% (1)
• C
  7% (2)
• D
  10% (3)
• E
  20% (6)

Explanation

CEF polarization occurs when multiple switches in different layers all use the same hashing inputs (e.g., all using Layer 3 source/destination IP), causing traffic to consistently follow the same path and defeating load balancing. To avoid polarization, adjacent layers must use different hash inputs so that traffic is redistributed at each layer. The recommended practice is: the core layer uses the default Layer 3 hash (source/destination IP - answer A), while the distribution layer uses Layer 3 AND Layer 4 information (source/destination IP + source/destination ports - answer F). This ensures the distribution layer re-hashes traffic differently from the core, breaking the polarization pattern. Options B, C, D, and E represent incorrect combinations that either duplicate hash inputs between layers or assign the more complex hash to the wrong layer.

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