This page outline how you can migrate from a competing product and keep the current DNS records.
Follow this guide if you are looking to migrate from another WHMCS DNS Manager module you currently have.
The competing module must be using BIND based nameserver.
You have root access to old nameserver
You have root access to new DirectAdmin server
Setup the DNS Suite Module with the proper DirectAdmin credentials
Go into the Admin Management Panel
addonmodules.php?module=dnssuite&action=syncremote
/var/named/
Copy the zipped file with all the DNS zones to your DirectAdmin server, now extract it to /var/named/ as well
Restart the DirectAdmin named, everything should load correctly if there is no syntax error in the zones.