Scenario: A Citrix Administrator configured a new router that requires some incoming and outgoing traffic to take different paths through it. The administrator notices that this is failing and runs…

Question

Options

• ALayer3
• BUSNIP
• CMAC-based forwarding (MBF)
• DUSIP

• A
  13% (8)
• B
  7% (4)
• C
  77% (46)
• D
  3% (2)

Explanation

MAC-based forwarding (MBF) causes the Citrix ADC to send return traffic back through the same interface/path it received the request on, using the source MAC address rather than consulting the routing table. This directly breaks asymmetric routing scenarios where incoming and outgoing traffic must take different paths - so disabling MBF forces the ADC to rely on the routing table instead, allowing the new router's path configuration to be respected.

Why the distractors are wrong:

• A. Layer3 - This enables IP routing between subnets on the ADC; disabling it would break routing entirely, making the problem worse.
• B. USNIP - "Use Subnet IP" controls whether the ADC uses a mapped subnet IP for server-side connections; it has no bearing on routing path selection.
• D. USIP - "Use Source IP" preserves the client's original source IP when the ADC connects to backend servers; again, unrelated to which physical path packets traverse.

Memory tip: Think of MBF as "reply the way you came" - the ADC stubbornly follows the MAC address back out the same door it received traffic from, ignoring the routing table. Any time a question mentions asymmetric routing failing on a Citrix ADC, MBF is the culprit to disable.

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