To change the number of firewall instances used by CoreXL, the cpconfig command must be used, followed by a reboot. CoreXL is a technology that improves the performance of the Security Gateway by using multiple cores to handle concurrent connections. The number of firewall instances determines how many cores are dedicated to CoreXL. The cpconfig command allows the administrator to configure various settings on the Security Gateway, including the number of firewall instances. After changing this setting, a reboot is required for the changes to take effect. The other commands are either incorrect or do not require a reboot.