“*** UnKnown can't find : Non-existent domain on NSLOOKUP” error occurs when the DNS reverse lookup zone for the particular network is either not configured or has corrupted.
In order to resolve this, we should create a reverse lookup zone. Also if you have existing devices you may have to create manual PTR entries on the new reverse lookup zone.
Let's resolve this issue using the following step by step guide.
Open the DNS management console (Start -> Administrative Tools -> DNS)
Go to the Reverse Zone Lookup folder. Right-click on it and select New Zone
New Zone Wizard will open up and click Next.
Select Primary Zone as the Zone Type and click Next.
Select the Zone Replication Scope based on your network setup. If you are not sure about forest configuration you can select To all DNS servers running on the domain controller in the domain. you can leave it to default and click Next.
Select the address type based on your requirement (Here I use IPV4) and Next.
Type the first three octets of your network IPV4 address range like 192.168.1 and click Next.
Select Allow only secure dynamic updates and click Next.
Click Finish and Restart the DNS Server service. Now for all the new systems, you add into the network you will not get the ““*** UnKnown can't find : Non-existent domain on NSLOOKUP” error. However, to fix this issue with existing network devices go to next steps
Right-click on the newly created reverse lookup zone and click New Pointer (PTR).
Provide the IP address and the Hostname and click OK. You will have to do this for all the older devices to make the DNS server aware of those systems.
If you are facing a "Default Server: UnKnown" issue my below article could help you resolve it.