Nodes assigned to the Decision Data Store service can use an external Cassandra cluster. So that data can be loaded into, or extracted from, the D-Node cluster, you must enable external connections. Once you have enabled this setting, you can connect to the D-Node cluster using third party or custom tools to do the data loading/extraction through the Thrift protocol on port 9160, or CQL3 Cassandra protocol on port 9042. Based on the schema the data is added to, it is stored through the Cassandra process. Cassandra being a distributed database, and configured to be fault tolerant to a degree, the data is distributed and replicated across the cluster and stored in SSTable format in the node's file system. When enabling external connections, you must provide the user name and password. A default user name (dnode_ext) is added when you enable external connections for the first time.