You need a DNS management tool where you can change and edit records for that domain. Are you saying you already have a public DNS server (the dedicated server you're talking about)? If so what software is it running?
That's the thing i have no idea, i do know with the dedicated server in WHM it looks like this:
But where those comes from I have no clue ?
I have the VPS set up completely isolated as in it is from scratch has nothing to do with the above.
It runs Centos6
But I don't know how those dns stuff works like where does ns.dns1.co.za come from ?