DnsSwitch

DnsSwitch is a perl script that can be used to switch the ip of a domain to other ip in case of failure. The script will run on the server that is hosting the nameservers for a domains and check that domain for availability over the HTTP protocol, if the server that hosts the domain responds then the script does nothing, if the server does not respond then the script replaces the ip of the domain with the ip of a backup server that hosts the domain.