If you use virtual hosts pointing to your htdocs Zabbix frontend, you don't have to setup additional frontends anywhere:
<VirtualHost *:80>
ServerName zabbix-cet.domain.com
DocumentRoot "/usr/local/apache2/htdocs"
php_value date.timezone CET
ErrorLog "logs/zabbix-cet.domain.com-error_log"
CustomLog "logs/zabbix-cet.domain.com-access_log" common
</VirtualHost>
<VirtualHost *:80>
ServerName zabbix-tokyo.domain.com
DocumentRoot "/usr/local/apache2/htdocs"
php_value date.timezone Asia/Tokyo
ErrorLog "logs/zabbix-tokyo.domain.com-error_log"
CustomLog "logs/zabbix-tokyo.domain.com-access_log" common
</VirtualHost>
<VirtualHost *:80>
ServerName zabbix-cet.domain.com
DocumentRoot "/usr/local/apache2/htdocs"
php_value date.timezone CET
ErrorLog "logs/zabbix-cet.domain.com-error_log"
CustomLog "logs/zabbix-cet.domain.com-access_log" common
</VirtualHost>
<VirtualHost *:80>
ServerName zabbix-tokyo.domain.com
DocumentRoot "/usr/local/apache2/htdocs"
php_value date.timezone Asia/Tokyo
ErrorLog "logs/zabbix-tokyo.domain.com-error_log"
CustomLog "logs/zabbix-tokyo.domain.com-access_log" common
</VirtualHost>