replicationFactor

The number of nodes in the DAX cluster. A replication factor of 1 will create a single-node cluster, without any read replicas. For additional fault tolerance, you can create a multiple node cluster with one or more read replicas. To do this, set ReplicationFactor to a number between 3 (one primary and two read replicas) and 10 (one primary and nine read replicas). If the AvailabilityZones parameter is provided, its length must equal the ReplicationFactor.

AWS recommends that you have at least two read replicas per cluster.