This is what is normally used for keeping databases in sync with each other.
http://dev.mysql.com/doc/refman/4.1/...uster-faq.html
or
http://www.howtoforge.com/mysql_database_replication

The only problem I see with ns 1 & 2 being different servers is that if they are both used simutaneously than the second (replicated) could have more data then the master.