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.

Wackamole operates on a cluster of tightly connected machines (all on the same LAN). It works by managing a pool of IP addresses that you expect to be available at all times. These IP addresses are virtual (meaning no machine has any of those IPs as its default IP address). Wackamole will work to ensure that all of the IP addresses in the pool are assigned as virtual IPs to the machines in the cluster. No IP address is held by more than one machine and every IP address is available.

This allows you to run 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.