Hello @miteshnettelnetwork ,
as a best practice you should add a second domain controller which will be placed in the new subnet (and ideally not on the same virtualization host as the existing domain controller). Using only one DC is a critical single point of failure as nothing will work anymore if this DC fails.
I am afraid you will not be able to simply switch the IP address on the existing DC without any impacts as all systems use this DC for authentication and have its IP stored in the DNS cache. So if you switch the IP address the systems will still try to connect to the old IP and therefore will run into authentication and DNS resolution issues.
The steps required for modifying all systems would have to be executed almost simultaneously:
1. Remove old IP address from DNS zone and register new ip address (ipconfig /registerdns) on DC
2. Modify DHCP settings to deploy new IP address (DNS server) to clients (clients would have to reboot or reconnect to the network to get the updated config)
3. Modify systems with static IP addressing to use new DNS IP address
If you add another domain controller and configure it to function in the same way as DC 1 you are able to switch more smoothly and you are able to fail back in case of errors. So this would be the recommended way.
3.
