The data under cn=monitor DIT helps in identifying and fixing various underlying problems. The cn=monitor provides information to find various problems such as performance and usage, LDAP operations or services for a Directory Proxy Server instance, remote services, connections, load balancing, JVM, connection handler thread, work queue, and various other threads.
To understand the layout of cn=monitor and description of each entry under it, refer to Monitoring Directory Proxy Server in Sun Directory Server Enterprise Edition 7.0 Reference.