Abstract: A distributed system includes multiple servers that various client devices access. Each server maintains a copy of a data object for access to the data object regardless of which server is accessed. Each server may modify a local copy of the data object, with the modifications propagated to other servers. A server generates a local version vector that includes pairs of a server identifier from whom modifications were received and a server-specific version identifier for the modifications. When a client device retrieves the data object, the client device transmits a client version vector for the data object including pairs of server identifiers and server-specific version identifiers from which the client device received version events for modifications to the data object. The server compares the local version vector to the client version vector to determine whether to transmit a local copy of the data object to the client device.