WN - DNS failover

Hej, sitter och funderar på failover.
Tänkte lägga det i dnsen, ungefär som en dnsleverantör utrycker det:

Citat:

Failover monitoring service works when you have two or more web servers running the same (or similar) web site.
First, you need the IP address for your domain, and get it working - then you add the failover monitor.
The failover monitor watches your web server(s) by hitting a URL you specify and looking for text in the results.
When the system detects that one of them is having an error, and the others aren't, it pulls the IP address out of the list.
If none of the IP's are responding and you have a failure IP/URL defined, then it points the site to the failure IP/URL.
If the system can't get to all of the IP's then it assumes that the fault is it's own connection - and it takes no action.
If any of your IP's come back online they are restored
This effectively and safely keeps your site online - even if one of your web servers is down.

Okej, låter bra.
Men hur får jag det att fungera med min bind9 server (freebsd, master zonerna ligger på en egen maskin på annan ort)?
Är det någon som har sett ett open source program, eller behöver jag koda ihop något eget?