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Note  The information in this topic applies only to a Microsoft Access database (.mdb).

Replicas (replica: A copy of a database that is a member of a replica set and can be synchronized with other replicas in the set. Changes to the data in a replicated table in one replica are sent and applied to the other replicas.) fall into three visibility types: global (global replica: A replica in which changes are fully tracked and can be exchanged with any global replica in the set. A global replica can also exchange changes with any local or anonymous replicas for which it becomes the hub.), local (local replica: A replica that exchanges data with its hub or a global replica but not with other replicas in the replica set.), and anonymous (anonymous replica: In an Access database, a special type of replica in which you don't keep track of individual users. The anonymous replica is particularly useful in an Internet situation where you expect many users to download replicas.). A replica's visibility type determines several issues for the replica. For instance, a replica's visibility determines what type of replicas you can create from it, whether it can act as the Design Master (Design Master: The only member of the replica set in which you can make changes to the database structure that can be propagated to other replicas.) in the replica set (replica set: The Design Master and all replicas that share the same database design and unique replica set identifier.), and how it handles conflicts during synchronization (synchronization: The process of updating two members of a replica set by exchanging all updated records and objects in each member. Two replica set members are synchronized when the changes in each have been applied to the other.). Visibility also determines which replicas that replica can synchronize with. You can't change a replica's visibility once you create the replica.

A global replica is the typical replica from which you can create all other types of replicas. Changes by a global replica are fully tracked and can be exchanged with any other global replica in the set. The global replica can also exchange changes with any local or anonymous replicas for which it becomes the hub (hub: A global replica to which all replicas in the replica set synchronize their changes. The hub serves as the parent replica.). The Design Master is a global replica. From a global replica, you can create replicas that are global, local, or anonymous. Replicas created from a global replica are global by default.

Local replicas synchronize only with their hub, a global replica. They are not permitted to synchronize with other replicas in the replica set. Other local replicas are not aware of the local replica. Only the hub replica is aware of local replicas, and only from it can you schedule an exchange with a local replica. All replicas created from a local replica will also be local and have the same parent replica.

An anonymous replica can synchronize with its parent, a global replica. Anonymous replicas subscribe by way of the Internet, and do not have any particular identity, but instead proxy their identity for updates to the publishing replica. Internet/intranet synchronization works well when the replica set remains small (fewer than 10 individual replicas) and the number of data inserts and updates are limited. Anonymous replicas provide a way of getting around this "limit on number of replicas" problem. In addition, using anonymous replicas helps to keep out unnecessary topology information about replicas that participate only occasionally. All replicas created from an anonymous replica will also be anonymous and have the same parent replica. Anonymous replicas are recommended for use on the Internet for mass distribution because system-tracking information is not maintained, and replica size is reduced. A global replica will not be able to schedule synchronizations with an anonymous replica.

All local and anonymous replicas always have a priority of 0. Therefore, if any of their changes conflict with the global hub replica, the changes will automatically lose in any conflict resolution process. If they convey a non-conflicting change to the hub, the hub assumes authorship of the change.