An aspect of Cassandra's architecture that demonstrates its AP CAP designation is in how each instance works together. A single-instance running in Cassandra is known as a node. A group of nodes serving the same dataset is known as a cluster or ring. Data written is distributed around the nodes in the cluster. The partition key of the data is hashed to determine it's token. The data is sent to the nodes responsible for the token ranges that contain the hashed token value.
The consistent hashing algorithm is used in many distributed systems, because it has intrinsic ways of dealing with changing range assignments. You can refer to Cassandra High Availability by Strickland R. (2014), published by Packt.
The partition key (formerly known as a row key) is the first part of PRIMARY KEY, and the key that determines the row’s token...