6.3 Describe Controller-Based, Software Defined Architecture (overlay, Underlay, and Fabric) 200-301 Practice Questions (Page 3)

Questions 11–15

1. 11application · medium

   A network engineer is troubleshooting an SDN deployment where the controller cannot communicate with a switch. The switch is connected to the management network. Which step should the engineer take first to verify the southbound channel?

   • AReboot the switch to reset the data plane.
   • BVerify that the northbound API is reachable from the switch.
   • CConfirm that the overlay network is carrying control traffic.
   • DCheck that the switch has the correct controller IP address and that the southbound protocol (e.g., OpenFlow) is enabled.
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2. 12expert · hard

   A service provider is deploying an SDN-based WAN with multiple overlays. The provider wants to offer different service levels to customers, such as low-latency for voice and high-bandwidth for video. The underlay is a shared IP/MPLS network. Which approach best ensures that each overlay receives the required performance?

   • AEncapsulate all overlays in a single VXLAN and use the same forwarding path.
   • BCreate a separate overlay for each service level and rely on the underlay's best-effort routing.
   • CUse the underlay's QoS mechanisms to prioritize traffic based on the overlay's markings.
   • DUse the controller to dynamically reroute all overlay traffic to avoid congestion.
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4. 13application · medium

   A network administrator is explaining SDN to a colleague. The administrator states that the controller has a global view of the network and can make forwarding decisions. Which statement best describes the role of the data plane in this architecture?

   • AThe data plane is responsible for maintaining the network topology.
   • BThe data plane forwards packets according to the rules installed by the controller.
   • CThe data plane makes all routing decisions independently.
   • DThe data plane communicates with applications via northbound APIs.
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5. 14application · medium

   A network architect is designing a fabric for a data center. The fabric will use a spine-and-leaf topology with an SDN controller. Which statement correctly describes the relationship between the fabric and the controller?

   • AThe fabric operates independently of the controller once the underlay is configured.
   • BThe fabric uses northbound APIs to communicate with the controller.
   • CThe controller manages the fabric by programming the leaf and spine switches through southbound APIs.
   • DThe controller replaces the spine switches in the fabric.
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6. 15expert · hard

   A network engineer is troubleshooting an SDN fabric where the controller is unable to program a specific switch. Other switches in the fabric are working correctly. The switch is reachable via ping from the controller. Which is the most likely cause of the issue?

   • AThe switch's data plane is faulty.
   • BThe overlay network is not carrying traffic to the switch.
   • CThe southbound protocol (e.g., OpenFlow) is not enabled or is misconfigured on the switch.
   • DThe northbound API is down on the controller.
   Reveal Solution Discussion Select an answer first