Hi,
Today i will show you how to create a simple dns failover with bind9, you will need 2 vps's with debian.
So on the first server and second server you just create a normal zone in named.conf
So your db file look like this:
On the second server i have created a script:
The script just ping's the mainserver 5 times, when it would fail the 5 times in a row it gonna change the zone file's, creating a folder and send a mail to you out (you need postfix and mailutils for this)
And the db.switched looks like this:
You just need to edit the scripts a bit and put it into a cronjob
Source: http://cdn.ikarusbasis.info/dl/failover.txt
Have fun with it <3