If you have DNS service from Rackfish, you can update your DNS as follows:
Managed DNS
Free changes and advice regarding all kinds of DNS management are included if you have our Managed DNS service. You need to contact our support and we will help you get everything right.
DNS in my.rackfish.com
If you have DNS in my.rackfish.com, you can manage your DNS settings by going to My Services - Web Hosting Services & Domains - DNS Services. The various services you have access to are listed here. You can either make the changes directly in my.rackfish.com, or you can make the changes via cPanel, which is linked from the page.
If you can't find it on your DNS service, contact our support for assistance!