The Threat Defense device cannot change its firewall mode while it has an active manager configuration. After unregistering the device from Management Center, the engineer must execute configure manager delete to remove the manager association and place the device in No Manager Mode. The engineer can then execute configure firewall transparent to change the operating mode. Changing firewall modes clears the device configuration because routed-mode and transparent-mode interface configurations are incompatible. After completing the conversion, the engineer must configure the Management Center association again with configure manager add and register the device. Options A and B are not valid Threat Defense CLI commands. Option D performs the actual mode conversion, but it is not the first required CLI command while the manager association remains configured. Cisco Threat Defense command reference

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