What action can a network administrator take to help mitigate the threat of VLAN hopping attacks?

What action can a network administrator take to help mitigate the threat of VLAN hopping attacks?

• Disable automatic trunking negotiation.
• Disable VTP.
• Enable PortFast on all switch ports.
• Configure all switch ports to be members of VLAN 1.

Explanation: There are two methods for mitigating VLAN hopping attacks:
disabling automatic trunking negotiation on switchports
turning trunking off on all unused nontrunk switchport

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