Database Software

For security reasons, we have two Oracle 9.i database servers (Windows Server 2003 as O/S):

We have a database server A in our internal network, which is our Intranet, too.

We have a database server B, out of our Intranet but in our internal network, which can be accessed through Internet and any Internet user with a certain password can insert, update or delete records.

Both database servers A and B have the same structure, but their data is different. Database A can be accessed from our Intranet and its records can only be updated for our Intranet users. Database B is only available for Internet users (out of our Intranet) and they also can update its records.

**We need that both databases have the same data at any time.**

Is it possible to REPLICATE in real time both database servers? Is there any set up or configuration that we must follow to achieve that?

Thanks in advance!