Abstract: Disclosed are methods of synchronizing changes in a directory service, comprising receiving a sync request comprising a token from a sync client and returning a response to the sync client comprising a token and changes. Embodiments include collecting and returning changes that are new to the sync client, collecting and returning changes from first and second directory servers, and returning a unified token. The changes may include changes to a dataset that is partitioned over first and second directory servers, and the partitioning may include entry-balancing. Also disclosed are embodiments of a directory service comprising first and second directory servers, each comprising a change set with changes, and a proxy server configured to collect and send changes in the change sets that are new to a sync client, and proxy server and a directory server for use in synchronizing changes in a directory service.