Hi,
I have a very good question and I would like to know if it is possible to be done.
I have 2 web server, the Main server backup it self into the Secondary server every day, now would it be possible for the firewall to be able to switch automatically from the Main to the Secondary server without a humain intervention in case the main server becomes unavailable and go back the Main server when it is back online.
The easiest way is to use netwatch changing the nat rule you are using now for redirection to the first web server.
As Jarda said, it is possible, but the main question becomes, how do you determine a server fault? That is stops responding to pings, or that it no longer is serving any web requests, or that it still servers web requests, but not any content.
A simple ping is easy to test for and use netwatch on, the other two require a more indepth test. You can write some scripts that will download a page every so often and take action based on the results.
Thank You very much both of you, I will look into it and do some test.