1. Add the new IP addresses on ISPConfig | Management | Server/Settings | Server/IP List
2. ISPConfig | ISP Manager | <website> | Basis | IP Address | choose the relevant IP from the drop-down list.
3. ISPConfig | DNS Manager | <domain name> | Domain | new.ip.address
4. ISPConfig | DNS Manager | <domain name> | Records | IP-adresse | new.ip.address