Syncronizing Databases at different Remote Location

I am new in the field of Database Management. Most of times i worked with Software development and Database Design.

I need some advice regarding database management.

I have three Database (DB) servers at different locations. suppose A, B and C as three servers. where as Z is a central server which have VPN to all other servers.

I have to insert/update records to central server Z if there is any insert/update in any of the A,B and C server.

Now I can write a JAVA code that when ever there is insertion/updation of record of A/B/C do same in central Server Z using JAVA sockets I can send records to central server where Socket server will listen and then insert or update records in DB.

But I come to know that there is a concept called Replication. 

I studied it and found that it is used for load balancing.  I dont need load balancing I only need to Syncronize only Two tables of all A,B,C servers to central server Z.

Please suggest how to move forward.(Open source solutions )

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Best Regards
Shakeel Abbas