What is cluster host?
A cluster host is a host that is configured to act as another host server within a cluster. This approach eliminates the danger inherent in a single point of failure and makes more efficient use of network resources.
A cluster host is a host computer that can support the various guest operating systems on a different physical computer. So if a physical computer fails due to maintenance or restart, the cluster host should be configured to support all of the guest operating systems on the original server. This is transparent to the end user and eliminates a possible single point of failure.