You misunderstand that it probably is trying to do a reverse lookup but your local dns server does not have any information. Here is how I do it:
1.) setup dnsmasq on a small ubuntu vm (this exercise left to the reader)
2.) edit /etc/dnsmasq.conf and add the dns servers for the remote sites/resource domain (assuming that they will answer your request of course) by tacking on lines that look like this at the end of the config:
so for 10.12.217.x ip addresses go to 10.12.217.10 (the dns server address for this subnet). I disable all dhcp options by commenting them out. Restart the service then use this machine as my dns host for scanning subnets.
Having the same issue. Subnets which are populated using neighbor scanning are not returning hostnames. The server which IPAM is installed on successfully resolves the IP's though.
Routable subnets are working fine with DNS.