cassandra-topologies.properties file
The PropertyFileSnitch snitch option uses the
cassandra-topologies.properties configuration file to determine which
datacenters and racks cluster nodes belong to. If other snitches are
used, the cassandra-rackdc.properties must be used. The snitch determines
network topology (proximity by rack and datacenter) so that requests are
routed efficiently and allows the database to distribute replicas
evenly.
Include every node in the cluster in the properties file, defining your datacenter names as in the keyspace definition. The datacenter and rack names are case-sensitive.
The cassandra-topologies.properties file must be copied identically to
every node in the cluster.
Example
This example uses three datacenters:
# datacenter One
175.56.12.105=DC1:RAC1
175.50.13.200=DC1:RAC1
175.54.35.197=DC1:RAC1
120.53.24.101=DC1:RAC2
120.55.16.200=DC1:RAC2
120.57.102.103=DC1:RAC2
# datacenter Two
110.56.12.120=DC2:RAC1
110.50.13.201=DC2:RAC1
110.54.35.184=DC2:RAC1
50.33.23.120=DC2:RAC2
50.45.14.220=DC2:RAC2
50.17.10.203=DC2:RAC2
# datacenter Three
172.106.12.120=DC3:RAC1
172.106.12.121=DC3:RAC1
172.106.12.122=DC3:RAC1
# default for unknown nodes
default =DC3:RAC1