Setup DNS Autodiscovery

Right click on the zone name, go to Properties and go to zone transfers tab.

You can allow zone transfers to device42 appliance IP only if you prefer.

Now, you can go back to your awesome device42 webconsole and go to Tools > Auto-discover > DNS.

Then add a new zone for autodiscovery and fill out following:

Name: Would be the zone name to be transferred, probably where you just allowed transfer.
Nameserver: FQDN or IP address for the DNS server. FQDN would work only if DNS is configured correctly from the console.
Auto Delete Enabled: This would delete records that were not found in new transfer and were found in old transfer. This would also delete any enteries that you have manually added for that zone in device42 and have not added to your DNS server yet.

You can save this and choose run now. New zone, IPs etc. should appear if you see success.
You can schedule to run this every day multiple times, just add the desired schedule.