Which of the following is NOT a way to resolve a conflicting public and private IP address in a Local Area Network (LAN)?

Changing the firewall settings on all devices is not a practical or effective way to resolve a conflict between public and private IP addresses within a Local Area Network (LAN). Typically, a firewall is designed to filter traffic and enforce security policies, and adjusting settings across all devices would not directly address the issue of IP address conflicts.

In contrast, toggling on Network Control Challenge or utilizing Authorization Hosts with Keywords are methods specifically designed to manage network configurations and can effectively help mitigate issues arising from IP address conflicts. These approaches focus on controlling access and ensuring that devices are correctly identified and authorized on the network, which is essential for maintaining proper communication between devices using different types of IP addresses.

Thus, option C is correct, as it highlights an ineffective method in comparison to other strategies aimed at resolving IP address conflicts in a LAN setup.