An indexer clustering requirement is that the cluster members must share the same license pool and license master. A license pool is a group of licenses that are assigned to a set of Splunk instances. A license master is a Splunk instance that manages the distribution and enforcement of licenses in a pool. In an indexer cluster, all cluster members must belong to the same license pool and report to the same license master, to ensure that the cluster does not exceed the license limit and that the license violations are handled consistently. An indexer cluster does not require shared storage, because each cluster member has its own local storage for the index data. An indexer cluster does not have to reside on a dedicated rack, because the cluster members can be located on different physical or virtual machines, as long as they can communicate with each other. An indexer cluster does not have to have at least three members, because a cluster can have as few as two members, although this is not recommended for high availability