DNS zones can be added manually or (preferrably) via DNS auto-discovery as discussed at: https://docs.device42.com/tools/setup-dns-autodiscovery/
DNS Zone Add/Edit page
The DNS Zones add/edit page can be reached via the main menu, Network -> DNS Zones. Click the “Add DNS Zone” button in the upper right to add a new zone. Give your zone a name, and specify the Nameserver for that zone. Optionally, you can specify the VRF Group that your new Zone belongs to, tags relevant to your new zone, and any relevant notes. Click “Save” in the bottom right when finished, and you’ll be brought back to the DNS Zones list page, where you will see your new zone along with any others that exist.
To define a DNS Zone, add/edit the zone specific fields show above.
Editing existing records
To edit an existing DNS Zone Record, click the name of the DNS Zone Record you’re trying to edit:
You can edit individual \records from the DNS Records list page, Network menu -> DNS Records