Sorry for my English google:)
I'm put into production 2 openldap masters, and I asked the same question Joćo Alfredo.

So, if the resultt of this search is the same on all master's this mean that all servers are consistents, right ?

Ok, the ldapsearch (ldapsearch-x-h Master1 ... and ldapsearch-x-h master2 ...) displays the same values of contextCSN for server ID, but what it proves that they are synchronized?

The question is, why master node, the ldapsearch ContextCSN displays of 2 servers (001 & 002)

Can be put in place a monitoring system to test the replication by performing 2 ldapsearchs, if even then synchronized values.