Change Installation Server

Hi,

May I know how to change the source of the installation server?

Let's say the sapgui installation server is set up on machineA. Then a failure happens on machineA, another sapgui installation server is set up on machineB.

my question:

1) what happen to those computers that are earlier installed using the installation server from machineA?

2) how to let these computers get updates from machineB?

thanks

regards,

xinlin