14.9.11 Packet Tracer - Layer 2 Vlan Security «2K 2026»

That’s where comes in. It’s the often-overlooked foundation of network defense.

On any port that should not be a trunk (i.e., all end-user ports), explicitly turn off trunking: 14.9.11 packet tracer - layer 2 vlan security

Never use VLAN 1 for anything. Not for native VLAN, not for management, not for users. VLAN 1 is the universal key to many Layer 2 attacks. Step 4: DHCP Snooping – Stopping the Rogue Server The Threat: An attacker plugs in a laptop running a rogue DHCP server. When legitimate clients broadcast for an IP, the rogue server replies first, giving them a malicious gateway (the attacker) or a bogus DNS server (phishing). That’s where comes in

Port Security.

Move the native VLAN to an unused, "dead-end" VLAN. Not for native VLAN, not for management, not for users

interface g0/1 switchport trunk native vlan 999 Then, ensure VLAN 999 exists but is used nowhere else. No user devices, no DHCP, no routing.

Take the time to run this lab. Break it on purpose. Watch the show port-security , show dhcp snooping binding , and show interfaces status err-disabled outputs.