6.3 Describe Controller-Based, Software Defined Architecture (overlay, Underlay, and Fabric) 200-301 Practice Questions (Page 7)

Questions 31–35

1. 31application · medium

   A company is deploying a software-defined fabric to support virtual machine mobility across data centers. The fabric uses VXLAN overlays over an IP underlay. Which benefit does the overlay provide in this scenario?

   • AIt increases the MTU of the physical network to accommodate larger frames.
   • BIt decouples tenant Layer 2 domains from the physical Layer 3 network, enabling VM mobility across sites.
   • CIt replaces the need for the underlay network entirely.
   • DIt eliminates the need for a controller in the fabric.
   Reveal Solution Discussion Select an answer first
2. 32application · medium

   A network engineer is troubleshooting a controller-based SDN deployment where the underlay uses OSPF for IP reachability. The engineer notices that when a new VLAN is added to a fabric edge switch, the controller must push the VLAN configuration to the switch, but the OSPF adjacencies remain unchanged. Which statement best explains why the OSPF adjacencies are unaffected?

   • AOSPF operates in the control plane, which is centralized on the controller, so the switch does not run OSPF.
   • BThe controller uses a southbound API to modify OSPF timers, so the adjacency state is preserved.
   • COSPF adjacencies are established over the overlay, so they are independent of any underlay changes.
   • DThe VLAN configuration is part of the data plane forwarding logic, while OSPF adjacencies are maintained by the control plane, which is separate.
   Reveal Solution Discussion Select an answer first
4. 33application · medium

   A service provider is designing a fabric to provide Layer 2 connectivity between customer sites across a Layer 3 IP backbone. The design uses VXLAN overlays. Which component is responsible for encapsulating and decapsulating tenant traffic at the edge of the fabric?

   • AThe spine switch performs all VXLAN encapsulation for traffic crossing the fabric.
   • BThe customer edge router encapsulates traffic before sending it to the provider network.
   • CThe fabric edge device, such as a leaf switch or VTEP, performs VXLAN encapsulation and decapsulation.
   • DThe SDN controller encapsulates tenant traffic before sending it to the underlay.
   Reveal Solution Discussion Select an answer first
5. 34application · medium

   A network administrator is comparing traditional networking to SDN. They notice that in SDN, the control plane is centralized on a controller, while in traditional networking, each device runs its own control plane. Which benefit does this centralization provide in an SDN architecture?

   • AIt eliminates the need for a data plane on each device.
   • BIt makes the network more resilient because the controller is a single point of failure.
   • CIt allows the controller to have a global view of the network and make consistent forwarding decisions.
   • DIt reduces the need for network monitoring because the controller handles all traffic.
   Reveal Solution Discussion Select an answer first
6. 35expert · hard

   A service provider is building a multi-tenant fabric. They need to support 4,000 VLANs per tenant and provide Layer 2 connectivity across multiple data centers. The underlay is a routed IP network. Which overlay technology best meets these requirements?

   • ATraditional VLANs with 802.1Q trunking
   • BGRE tunnels
   • CVXLAN
   • DMPLS L2VPN
   Reveal Solution Discussion Select an answer first