Para conectarse a un conjunto de réplicas principal, use el shell mongo --host opción:
mongo --host replicaSetName/host1[:porthost1],host2[:porthost1],host3[:porthost3],etc
Por ejemplo:
$ mongo --host rs1/john.local:27019,john.local:27018
MongoDB shell version: v3.4.9
connecting to: mongodb://john.local:27019,john.local:27018/?replicaSet=rs1
2017-10-12T14:13:03.094+0000 I NETWORK [thread1] Starting new replica set monitor for rs1/john.local:27019,john.local:27018
2017-10-12T14:13:03.096+0000 I NETWORK [thread1] Successfully connected to john.local:27019 (1 connections now open to john.local:27019 with a 5 second timeout)
2017-10-12T14:13:03.096+0000 I NETWORK [thread1] Successfully connected to john.local:27018 (1 connections now open to john.local:27018 with a 5 second timeout)
rs1:PRIMARY> db
test
rs1:PRIMARY>
Nota: De las versiones 3.4.2 a 3.4.10 hubo un error (SERVER-28072) que impedía especificar la base de datos después de usar --host o --port.
