How to add users to a domain?

Question

Active Directory

Hello,
How to enter users into a domain that is on a different network? there is a network 172.16.2.0/24 in it there are users which should be entered into the domain. The AD server is located on the 172.16.3.0/24 network, the networks are routed among themselves. How in that case to enter users into the domain? if you specify the static DNS address of the AD server directly in the network interface settings, then the input is feasible, but if you receive addresses via dhcp, then . input is not feasible, there is no invitation to enter the login and password of the domain administrator .... you need to configure the DNS server, but how?
to a request from the network 172.16.2.0/24 nslookupp, the server name says that it is not found, how to configure DNS?