Match each Layer 2 protection feature to its most accurate purpose.

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Layer 2 protection features are essential mechanisms in Cisco switching environments designed to secure the data link layer from common attacks and misconfigurations. Port Security restricts the number of MAC addresses learned on a switch port, preventing unauthorized devices from flooding the MAC address table and causing denial of service. BPDU Guard protects the Spanning Tree Protocol topology by shutting down ports that receive unexpected BPDUs, which are typically sent by switches and can cause topology loops if introduced on edge ports. DHCP Snooping monitors DHCP traffic to block rogue DHCP servers and builds a trusted binding table that maps IP addresses to MAC addresses and switch ports. Dynamic ARP Inspection (DAI) leverages this binding table to validate ARP packets, preventing ARP spoofing attacks that can redirect traffic or cause man-in-the-middle scenarios. Each Layer 2 protection feature addresses a specific security concern. Port Security enforces MAC address limits per port, effectively blocking unauthorized devices. BPDU Guard disables ports that receive BPDUs unexpectedly, protecting the STP topology from accidental or malicious loops. DHCP Snooping filters DHCP messages, allowing only trusted DHCP servers to assign IP addresses and preventing rogue servers from disrupting network IP configuration. DAI uses the DHCP Snooping binding table to verify ARP requests and replies, ensuring that only valid ARP traffic is forwarded. This layered approach ensures that different attack vectors at Layer 2 are mitigated by the appropriate feature. A common exam trap is confusing the purposes of these features or assuming they overlap in functionality. For example, some candidates mistakenly believe DHCP Snooping prevents MAC flooding or that BPDU Guard protects against ARP spoofing. In practice, each feature targets a distinct threat: Port Security controls MAC address usage, BPDU Guard protects STP topology, DHCP Snooping secures DHCP assignments, and DAI validates ARP traffic. Understanding these distinctions is critical for correctly matching features to their purposes and for designing secure Cisco switched networks that resist Layer 2 attacks.

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