We have had a good discussion on what replica set is in Chapter 1, Installing and Starting the Server in the recipe Starting multiple instances as part of a replica set, and we saw how to start a simple replica set. In the recipe Interprocess security in Mongo in this chapter, we saw how to start a replica set with interprocess authentication. To be honest, that is pretty much what we do in setting up a standard replica set. There are a few configurations that one must know and should be aware of how it affects the replica set's behavior. Note that we still are not discussing tag aware replication in this recipe and it would be taken up later in this chapter as a separate recipe Building tagged replica sets.