1. Firewall Configuration: /etc/csf/csf.conf - This configuration file controls traffic flow and blocks unauthorized access and attacks.2. MySQL Configuration: /etc/my.cnf - This file optimizes memory usage and prevents server slowdowns under heavy load.3. Apache Web Server: /etc/apache2/conf/httpd.conf - Proper configuration improves speed and security by efficiently handling website requests.4. FTP Server Configuration: /etc/pure-ftpd.conf - This file controls access permissions and prevents unauthorized file uploads/downloads.