The first server that the client meets is the Front Server. This server holds information about users and message servers.
The information for the user is:

Contact List information
The information about the servers is:
When user is served by some server the information i written down to:


The Message Server is the second server that the client meets. This is the server that is responsible of redirecting instant messages through the whole network. This server keeps information about the users served by it:
Also every MS server keeps information about the users in the contact list of the client it is serving
This server holds information about the messages and the sessions
When the client tries to enter MS the MS server checks his/her credentials and it they are ok it creates IM_SESS record and deletes IM_SERVER_USER record