As a network administrator, you have discovered that certain devices within the organization are being configured with incorrect network settings leading to connectivity issues and potential security vulnerabilities. This misconfiguration is suspected to be a result of an unauthorized entity. Which technique should be implemented to prevent this entity from issuing network settings to the organization's devices?
Disable unnecessary ports on network switches
Enable a feature on switches to inspect and validate IP address assignments
Modify the external firewall's settings to a stricter security profile
Upgrade the encryption protocols used for sensitive communications