Preparation Wizard is a great tool that helps troubleshoot Active Directory replication issues. The tool scans the existing network, identifies the source of AD replication errors and provides links to knowledge based articles that explain how to correct these issues. In order to identify the source of Active Directory replication errors, Preparation Wizard uses LDAP, DNS queries and WMI to contact each server in the network and run a set of checks to verify that AD replication is functioning correctly. In addition, the tool specifically looks for events that indicate Active Directory replication problems.
Supporting doc and other resources on troubleshooting Active Directory replication: