replica question

Hi,

I have the following situation

Machine - A equiped with
- a database
- Internet application that receives records and stores them into a
table on this machine

Machine - B equiped with
- the same database
- the same internet application but it only receives records when
machine A is down

What I would like to achieve is that the tables in both databases are
kept consistent.

How to do this with postgres ?

Do a write a C-program for that that is started by a trigger ?

Thanks,

Feite Brekeveld