This is the review of my server-manager:
my gateway is called Linux and his Ip is 192.168.0.2
Review configurationNetworking Parameters 
Server Mode serveronly 
Local IP address / subnet mask 192.168.0.254/255.255.255.0 
Gateway 192.168.0.2 
Additional local networks 192.168.0.0/255.255.255.0 
DHCP server disabled 
Server names 
DNS server 192.168.0.254 
Web server www.***.be 
Proxy server proxy.***.be:3128 
FTP server ftp.***.be 
SMTP, POP, and IMAP mail servers mail.***.be 
Domain information 
Primary domain ***.be 
Virtual domains ***.be 
Primary web site 
http://www.***.be 
Server manager 
http://faxserver/server-manager/ User password panel 
http://faxserver/user-password/ Email Addresses useraccount@***.be
firstname.lastname@***.be
firstname_lastname@***.be
Do I have to change DNS server into 192.168.0.2?
Grtz