Can you reset a client connecting to a remote Site DC back to it's local Site DC when it becomes available again?

Hi,

Two part question:

In W2K AD and I expect W2003 AD, a client computer when logging in tries to
use a local Site DC for authentication. If none, is available, how does it
determine which DC it should authenticate to? The following article
explains the process but I wonder if it is completely correct:

http://www.windowsitpro.com/Windows/...935/37935.html

Our experience has found that the DC's selected is not the fastest
responding (following network topology). I've read various articles, but
still not clear as to how that DC is selected. E.g. is it taking the first
15 DC, in DNS, based on alphabetical order, to ping, to see which one is the
closest? If so, is there a way to change this mechanism?

Once a client has information about which DC it is using,

how long is it cached?
does a reboot clear the cache? If not, is there a way to force a client the
next time the user logs in, to go and validate if a DC is available in the
Site?

Thanks for any input in advance,

Ed