6.2 Compare Traditional Networks with Controller-Based Networking 200-301 Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   A network engineer is comparing how a traditional router and a controller-based switch forward packets. In the traditional router, the forwarding decision is made by the router's own CPU or hardware. In a controller-based switch, how is the forwarding decision typically made for a packet that matches an existing flow entry?

   • AThe switch uses OSPF to determine the next hop and forwards the packet.
   • BThe switch forwards the packet according to the flow entry in its local flow table.
   • CThe switch floods the packet out all ports to ensure delivery.
   • DThe switch sends the packet to the controller for a forwarding decision every time.
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2. 7application · medium

   In a controller-based network, a switch receives a packet whose destination MAC address is not in its forwarding table. How does the switch handle this packet?

   • AIt drops the packet and sends an error message to the source
   • BIt forwards the packet to the controller to determine the correct output port
   • CIt buffers the packet until the destination MAC address is learned from a later frame
   • DIt floods the packet out all ports except the ingress port, as in a traditional switch
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4. 8application · medium

   A network engineer is troubleshooting a routing loop in a campus network that uses OSPF. The engineer suspects that a misconfigured router is advertising incorrect routes. In a traditional network, where would the engineer need to look to identify the source of the incorrect route advertisement?

   • AOn the network management system, because it dynamically updates OSPF routes on all routers
   • BOn each router individually, examining the OSPF configuration and routing table
   • COn the centralized controller, reviewing the flow table entries pushed to all routers
   • DOn the core switch, because it maintains the master routing table for the entire OSPF domain
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5. 9application · medium

   A network engineer is comparing failure handling between a traditional OSPF network and a controller-based network. In the traditional network, a link fails and OSPF converges by having each router recalculate routes. In the controller-based network, the same link fails. How does the controller-based network typically handle this failure?

   • AThe network automatically reverts to a spanning tree topology to avoid loops during the failure.
   • BEach switch independently reruns OSPF and updates its own routing table.
   • CThe switches use BFD to detect the failure and then use fast reroute to switch to a backup path without controller involvement.
   • DThe controller recalculates the affected paths and updates the flow tables on the relevant switches.
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6. 10expert · hard

   A network team is migrating from a traditional network to a controller-based network. They have a mix of legacy switches that do not support OpenFlow and newer switches that do. The team wants to manage all devices centrally. Which approach is most practical?

   • AReplace all legacy switches with OpenFlow-capable switches before implementing the controller.
   • BUse a controller that supports hybrid mode, managing OpenFlow-capable devices directly and using NETCONF or CLI for legacy devices.
   • CImplement a separate controller for legacy devices and another for OpenFlow devices.
   • DUse only traditional protocols and ignore the controller for legacy devices.
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