Changing the DNS settings on the PCS device takes effect immediately and does not requires a Service restart or reboot. After changing the server IP, an info message "Updating DNS/WINS settings for node(s) node-name" is displayed in the Admin log.
Admin log example:
ADM20580 Date Time - ive - [IVE IP ADD] Root::User Name(Admin Role)[Admin Realm] - First DNS server changed from X.X.X.X to Y.Y.Y.Y for node <node name>.
It is possible that after changing the DNS server settings on a PCS device a brief disconnection or outage can occur. It would be best to make changes of this type during off peak hours.