The Agent uses either the last known IP address, DNS name, or NetBIOS name of the ePO server. If you change any one of these, ensure that the Agents have a way to locate the server. The easiest way to do this is to retain the existing DNS record and change it to point to the new IP address of the ePO server. After the Agent is able to successfully connect to the ePO server, it downloads an updated SiteList.xml with the current information.
In your case, if you change the DNS name but the IP is staying the same, there should be no issue at all but you could always re-direct the existing DNS record just to be 100%.
I got it.
This is what I intend to do. Change the name of the server machine and the DNS name. Keep only the IP.