The present invention provides a directory server system comprising: a directory
server for storing an attribute of an entry; an entity monitor being connected
to the directory server for monitoring an entity, so that if a change in a state
of the entity appears, then the entity monitor instructs the directory server to
renew an attribute of a corresponding entry to the entity; and a directory renewal
history storage device being connected to the directory server for storing a renewed
attribute of the entry as attribute renewal history informations.