UCS 2.4 - Univention

2 Domain concept
2.2.7 Mobile client
A mobile client offers a Linux desktop like a managed client, includes the last three passwords in its
cache and is a member of the UCS domain. However, it also offers the possibility of maintaining software
specially suited to notebook hardware.
2.2.8 Thin Client
A thin client is a diskless computer which is booted over the network and displays applications run on a
terminal server (Linux or Windows).
There is also no operating system installed on the thin client, which means that it requires very little
maintenance.
2.3 System roles in Windows domains
In a Windows NT domain, which can be provided by UCS using the Samba software, there must always be
a primary domain controller (PDC). There can also be backup domain controllers (BDC), member servers
and clients. The PDC provides the password database. BDCs retrieve a copy of the password database
from the PDC so that they can take some of the load off the PDC or take over its role in the case of a
collapse. The copies must not, however, be changed directly. Changes are usually always performed on
the originals on the PDC and then replicated on the BDCs. In a Windows NT domain there can only be
one original password database. There can thus only be one PDC. A member server offers services such
as file storage. In contrast to the PDC and BDCs, it does not have a password database.
2.3.1 How are these roles integrated in the UCS concept?
The LDAP directory is used in UCS as a password database and for further administrative tasks in the
Windows domain. As the LDAP directory in which the changes should be made is usually provided by
the DC master, it also usually accepts the role of the PDC. BDC are usually found on the DC backup or
DC slave. Any deviations from this pattern are usually implemented with a LDAP referral, with the help of
which the PDC can make changes in the LDAP directory on the DC master. Replication is not possible
between Windows NT-based domain controllers and UCS-based ones. For this reason, the PDC and all
BDCs in a UCS-based Windows domain need to be UCS-based, whilst member servers can be operated
with both UCS and Windows. The PDC and BDCS identify themselves as such to the Windows client
so that Windows client can execute operations on the PDC where the user database is changed (e.g.,
changing a user password). The replication of the password database is performed by the replication of
the LDAP directory. The replication is automatically set up using the system role which you specify during
the installation of a computer. Manual configuration is then not necessary if you add a further server to
the domain at a later point in time. Servers and clients on which a Microsoft Windows operating system is
installed locally are administrated as Windows computers in the LDAP directory.
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