A traditional Nutanix cluster requires a minimum of three nodes, but Nutanix also offers the option of a two-node cluster for ROBO implementations and other situations that require a lower cost yet high resiliency option. Unlike a one-node cluster (see Single-Node Clusters), a two-node cluster can still provide many of the resiliency features of a three-node cluster. This is possible by adding an external Witness VM in a separate failure domain to the configuration (see Configuring a Witness (two-node cluster)). Nevertheless, there are some restrictions when employing a two-node cluster. The following links will provide you guide lines and information abut configuring the two node clusters:
The second link contains a video about the topic.
Ask any questions to clarify any concerns about the the two node clusters.