Some customers prefer to manage their own DNS so will opt to use a third party DNS service. This is completly fine and is fully compatible with our web hosting service, this means of course that you're fully responsible for the domains DNS and will need to make the required changes to point the domain name to your web hosting space with us.
What you will need to change is the A record for the domain to the IP address of the web server that you're hosted on, you will find this IP in your customer portal under the account details for your service, of course if you get stuck with this or have any questions please just let us know.