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350-401 · Question #658

350-401 Question #658: Real Exam Question with Answer & Explanation

The correct answer is B: Layer 2 Flooding. Layer 2 Flooding in Cisco SD-Access Layer 2 Flooding is the correct answer because it is specifically designed within Cisco SD-Access to propagate ARP broadcasts and link-local frames (such as DHCP, multicast, etc.) across the fabric, enabling silent hosts - devices that don't in

Submitted by andreas_gr· Mar 6, 2026Infrastructure

Question

Which feature Is used to propagate ARP broadcast, and link-local frames across a Cisco SD- Access fabric to address connectivity needs for silent hosts that require reception of traffic to start communicating?

Options

  • ANative Fabric Multicast
  • BLayer 2 Flooding
  • CSOA Transit
  • DMultisite Fabric

Explanation

Layer 2 Flooding in Cisco SD-Access

Layer 2 Flooding is the correct answer because it is specifically designed within Cisco SD-Access to propagate ARP broadcasts and link-local frames (such as DHCP, multicast, etc.) across the fabric, enabling silent hosts - devices that don't initiate traffic - to receive packets and begin communicating. Without this feature, the LISP control plane used by SD-Access cannot map unknown hosts since they've never sent traffic to register their location.

Why the distractors are wrong:

  • A. Native Fabric Multicast handles efficient multicast traffic delivery within the fabric, not ARP/broadcast propagation for silent hosts.
  • C. SOA Transit is not a standard Cisco SD-Access term and does not relate to this function.
  • D. Multisite Fabric refers to connecting multiple SD-Access fabric domains together, addressing inter-site connectivity rather than silent host discovery within a single fabric.

Memory Tip: Think of the word "Flood" - just like water flooding a room reaches every corner, Layer 2 Flooding ensures broadcast frames reach every corner of the fabric, "waking up" silent hosts that are waiting to receive before they speak. 🌊

Topics

#SD-Access#L2 Flooding#ARP Broadcast#Silent Hosts

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