Hello, The following is my PDC and BDC some setting: PDC: local master = yes os level = 65 domain master = yes preferred master = yes domain logon = yes BDC: local master = no os level = 33 domain master = no preferred master = no domain logon = yes I has windows xp sp1(created in vmware + fc5(created in vmware)+Samba x2+ LDAP x2(Replication) for testing. http://www.wilson-kwok.com/ldap.GIF I turned off BDC and PDC work find when user login, but I turned off PDC and user cannot login to BDC, can someone tell me what is the problem ? Thanks -- By linking web mail system