Thanks Till for your response.
I do not have own DNS.
I have my own I.P. (xxx.xxx.xxx.xxx)
This my server config:
In Server Config :
Network Configuration (checked)
IP Address xxx.xxx.xxx.xxx (my I.P.)
Nameservers 192.168.2.3 (the gateway in my router for the server)
Please you can say if this configuration is correct ?
I have to add some DNS in ISPConfig ?
Thank you for answering and your excellent work.