Setting the Replication Slave Configuration
On a replication slave, you must establish a unique server ID. If this has not already been done, this
part of slave setup requires a server restart.
If the slave server ID is not already set, or the current value conflicts with the value that you have
chosen for the master server, you should shut down your slave server and edit the configuration to
specify a unique server ID. For example:
After making the changes, restart the server.
If you are setting up multiple slaves, each one must have a unique server-id  value that
differs from that of the master and from each of the other slaves. Think of server-id 
values as something similar to IP addresses: These IDs uniquely identify each server instance in the
community of replication partners.
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