Final answer:
Switching from dynamic allocation to automatic allocation in DHCP reduces network traffic related to periodic lease renewal messages to zero.
Step-by-step explanation:
In a DHCP network, the lease renewal process involves the client renewing its IP address lease with the DHCP server at a regular interval. With dynamic allocation, the client sends a lease renewal request to the server before the lease expires. This renewal process generates network traffic as both client and server exchange messages. However, in automatic allocation, the lease renewal process is eliminated because the client is assigned a lease for an infinite duration. As a result, network traffic related to periodic lease renewal messages is reduced to zero in automatic allocation compared to dynamic allocation.