DSM 7.1 DNS/Domain Issue

[sysadm1n42]

I purchased a Synology for a small client to use the Synology directory server with DNS. I have set up a few of these but have never run into an issue. When I attached my first workstation to the domain, Welcome to Domain! then I receive an error unable to communicate with the DC.

Please help, we were scheduled to go live with the Synology last week.

I check DNS by running nslookup, Server is unknown

with the correct address for my Synology.

 

[Rusty]

One of the 1st questions that come to mind is firewall and network traffic. Are you sure that UDP/53 traffic is allowed and running fine from the client to the server side?