The ICC has two servers, the main server chessclub.com, and
the backup server queen.chessclub.com. If you have an account
on the main server, you automatically get an account on the backup
server as well. Your two accounts will have the same password, the
same ratings (usually), and the same expiration date, but
may have separate finger notes, history list, and game library.
If you play a rated game on the backup server, the result will
not affect your rating on the main server. The games themselves are
not transferred between servers, nor will they appear in your history
list on the other server. Games adjourned on one server must be finished on
the same server. Messages and other player data such as finger notes
are not transferred between servers. Password changes are
transferred.
Registrations, first-logins for new accounts, and extensions can only
be done at the main server. Once a new account is created and used
for the first time at the main server, it is copied to the other
server. You can use both servers at the same time if you want to, but
if one is full it might help if you exit and just use the other one.
Chekel commands are best done on the main server.
Each server is designed to operate smoothly even when the other
one is down or unreachable. In such a case, the delay before
game results from one server are processed by the other will make
ratings appear to change somewhat unpredictably.