increase in time between domain server and controllers
what will happen if time between domain server and controllers increase in an internal time synchronization configuration?
But a number of other very serious problems can start to happen. As Stephan says, the windows authentication service will begin to fail. This in turn causes other services to fail because they cannot log in. In extreme cases, OPC-DA and History access between node will fail, rebooting the operator stations will kick them off the domain network and you could be unable to log in to any clients or servers.
Don't let this happen. Fix the time synch settings and make sure all the controllers, clients and servers are at the correct time.