Wackamole is an interesting application that helps with making a cluster highly available. It runs a service using multiple DNS RR records without the worry of one of the machines crashing — if the machine crashes, the virtual IP addresses it was responsible for will be managed by the remaining machines in the cluster. Wackamole is quite unique in that it operates in a completely peer-to-peer mode within the cluster. From the project home page:

Wackamole is an application that helps with making a cluster highly available. It manages a bunch of virtual IPs, that should be available to the outside world at all times. Wackamole ensures that a single machine within a cluster is listening on each virtual IP address that Wackamole manages. If it discovers that particular machines within the cluster are not alive, it will almost immediately ensure that other machines acquire these public IPs. At no time will more than one machine listen on any virtual IP. Wackamole also works toward achieving a balanced distribution of number IPs on the machine within the cluster it manages.

Download wackamole software

Visit the wackamole project:

=> wackamole web site