This section provides more in-depth information on replication conflicts than presented in earlier sections, so that administrators can understand the mechanisms and possible scenarios behind these conflicts.
Updates to Directory Server entries in a replication topology may happen independently, since replication guarantees only eventual consistency, not strong consistency. The eventual consistency model also means that conflicting changes can be applied at different directory server instances. In most cases, the Directory Server is able to resolve these conflicts automatically and in a consistent manner (i.e., all directory server instances in a replication topology will resolve each and every conflict the same way). However, in some scenarios, as seen below, manual administrative action is required. For any of these unresolved conflicts, the administrator is notified via administrative alerts.
On a high-level, the conflict resolution algorithm tries to resolve conflicts as if the operations causing the conflict in a distributed environment has been applied to a single directory server instance. For example, if the same entry is added to two different directory server instances at about the same time, then once these operations have been replicated, both directory servers will keep only the entry that was added first. The following figure highlights the differences between standalone versus replicated environments.