<s>
Active	B-Protocol
Directory	I-Protocol
(	O
AD	O
)	O
is	O
a	O
directory	O
service	O
developed	O
by	O
Microsoft	O
for	O
Windows	B-General_Concept
domain	I-General_Concept
networks	O
.	O
</s>
<s>
It	O
is	O
included	O
in	O
most	O
Windows	B-Device
Server	I-Device
operating	B-General_Concept
systems	I-General_Concept
as	O
a	O
set	O
of	O
processes	B-Operating_System
and	O
services	O
.	O
</s>
<s>
Initially	O
,	O
Active	B-Protocol
Directory	I-Protocol
was	O
used	O
only	O
for	O
centralized	O
domain	O
management	O
.	O
</s>
<s>
However	O
,	O
Active	B-Protocol
Directory	I-Protocol
eventually	O
became	O
an	O
umbrella	O
title	O
for	O
a	O
broad	O
range	O
of	O
directory-based	O
identity-related	O
services	O
.	O
</s>
<s>
A	O
server	O
running	O
the	O
Active	B-Protocol
Directory	I-Protocol
Domain	O
Service	O
(	O
AD	B-Protocol
DS	I-Protocol
)	O
role	O
is	O
called	O
a	O
domain	B-General_Concept
controller	I-General_Concept
.	O
</s>
<s>
It	O
authenticates	O
and	O
authorizes	O
all	O
users	O
and	O
computers	O
in	O
a	O
Windows	B-General_Concept
domain	I-General_Concept
type	O
network	O
,	O
assigning	O
and	O
enforcing	O
security	O
policies	O
for	O
all	O
computers	O
,	O
and	O
installing	O
or	O
updating	O
software	O
.	O
</s>
<s>
For	O
example	O
,	O
when	O
a	O
user	O
logs	B-General_Concept
into	I-General_Concept
a	O
computer	O
that	O
is	O
part	O
of	O
a	O
Windows	B-General_Concept
domain	I-General_Concept
,	O
Active	B-Protocol
Directory	I-Protocol
checks	O
the	O
submitted	O
username	O
and	O
password	O
and	O
determines	O
whether	O
the	O
user	O
is	O
a	O
system	B-Application
administrator	I-Application
or	O
normal	O
user	O
.	O
</s>
<s>
Also	O
,	O
it	O
allows	O
management	O
and	O
storage	O
of	O
information	O
,	O
provides	O
authentication	O
and	O
authorization	O
mechanisms	O
and	O
establishes	O
a	O
framework	O
to	O
deploy	O
other	O
related	O
services	O
:	O
Certificate	O
Services	O
,	O
Active	B-Protocol
Directory	I-Protocol
Federation	O
Services	O
,	O
Lightweight	O
Directory	O
Services	O
,	O
and	O
Rights	O
Management	O
Services	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
uses	O
Lightweight	B-Protocol
Directory	I-Protocol
Access	I-Protocol
Protocol	I-Protocol
(	O
LDAP	B-Protocol
)	O
versions	O
2	O
and	O
3	O
,	O
Microsoft	O
's	O
version	O
of	O
Kerberos	B-Protocol
,	O
and	O
DNS	B-Protocol
.	O
</s>
<s>
Like	O
many	O
information-technology	O
efforts	O
,	O
Active	B-Protocol
Directory	I-Protocol
originated	O
out	O
of	O
a	O
democratization	O
of	O
design	O
using	O
Request	O
for	O
Comments	O
(	O
RFCs	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
LDAP	B-Protocol
underpins	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
Also	O
,	O
X.500	B-Protocol
directories	I-Protocol
and	O
the	O
Organizational	B-Protocol
Unit	I-Protocol
preceded	O
the	O
Active	B-Protocol
Directory	I-Protocol
concept	O
that	O
makes	O
use	O
of	O
those	O
methods	O
.	O
</s>
<s>
The	O
LDAP	B-Protocol
concept	O
began	O
to	O
emerge	O
even	O
before	O
the	O
founding	O
of	O
Microsoft	O
in	O
April	O
1975	O
,	O
with	O
RFCs	O
as	O
early	O
as	O
1971	O
.	O
</s>
<s>
RFCs	O
contributing	O
to	O
LDAP	B-Protocol
include	O
RFC	O
1823	O
(	O
on	O
the	O
LDAP	B-Protocol
API	B-General_Concept
,	O
August	O
1995	O
)	O
,	O
RFC	O
2307	O
,	O
RFC	O
3062	O
,	O
and	O
RFC	O
4533	O
.	O
</s>
<s>
Microsoft	O
previewed	O
Active	B-Protocol
Directory	I-Protocol
in	O
1999	O
,	O
released	O
it	O
first	O
with	O
Windows	B-Application
2000	I-Application
Server	O
edition	O
,	O
and	O
revised	O
it	O
to	O
extend	O
functionality	O
and	O
improve	O
administration	O
in	O
Windows	B-Application
Server	I-Application
2003	I-Application
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
support	O
was	O
also	O
added	O
to	O
Windows	B-Application
95	O
,	O
Windows	B-Application
98	O
and	O
Windows	B-Device
NT	I-Device
4.0	O
via	O
patch	O
,	O
with	O
some	O
features	O
being	O
unsupported	O
.	O
</s>
<s>
Additional	O
improvements	O
came	O
with	O
subsequent	O
versions	O
of	O
Windows	B-Device
Server	I-Device
.	O
</s>
<s>
In	O
Windows	B-Device
Server	I-Device
2008	I-Device
,	O
additional	O
services	O
were	O
added	O
to	O
Active	B-Protocol
Directory	I-Protocol
,	O
such	O
as	O
Active	B-Protocol
Directory	I-Protocol
Federation	O
Services	O
.	O
</s>
<s>
The	O
part	O
of	O
the	O
directory	O
in	O
charge	O
of	O
the	O
management	O
of	O
domains	O
,	O
which	O
was	O
previously	O
a	O
core	O
part	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
was	O
renamed	O
Active	B-Protocol
Directory	I-Protocol
Domain	I-Protocol
Services	I-Protocol
(	O
ADDS	O
)	O
and	O
became	O
a	O
server	O
role	O
like	O
others	O
.	O
</s>
<s>
"	O
Active	B-Protocol
Directory	I-Protocol
"	O
became	O
the	O
umbrella	O
title	O
of	O
a	O
broader	O
range	O
of	O
directory-based	O
services	O
.	O
</s>
<s>
According	O
to	O
Byron	O
Hynes	O
,	O
everything	O
related	O
to	O
identity	O
was	O
brought	O
under	O
Active	B-Protocol
Directory	I-Protocol
's	O
banner	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Services	I-Protocol
consist	O
of	O
multiple	O
directory	O
services	O
.	O
</s>
<s>
The	O
best	O
known	O
is	O
Active	B-Protocol
Directory	I-Protocol
Domain	I-Protocol
Services	I-Protocol
,	O
commonly	O
abbreviated	O
as	O
AD	B-Protocol
DS	I-Protocol
or	O
simply	O
AD	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Domain	I-Protocol
Services	I-Protocol
(	O
AD	B-Protocol
DS	I-Protocol
)	O
is	O
the	O
foundation	O
of	O
every	O
Windows	B-General_Concept
domain	I-General_Concept
network	O
.	O
</s>
<s>
The	O
server	O
running	O
this	O
service	O
is	O
called	O
a	O
domain	B-General_Concept
controller	I-General_Concept
.	O
</s>
<s>
A	O
domain	B-General_Concept
controller	I-General_Concept
is	O
contacted	O
when	O
a	O
user	O
logs	B-General_Concept
into	I-General_Concept
a	O
device	O
,	O
accesses	O
another	O
device	O
across	O
the	O
network	O
or	O
runs	O
a	O
line-of-business	O
Metro-style	O
app	O
sideloaded	B-Protocol
into	O
a	O
device	O
.	O
</s>
<s>
Other	O
Active	B-Protocol
Directory	I-Protocol
services	I-Protocol
(	O
excluding	O
LDS	O
,	O
as	O
described	O
below	O
)	O
as	O
well	O
as	O
most	O
of	O
Microsoft	O
server	O
technologies	O
rely	O
on	O
or	O
use	O
Domain	O
Services	O
;	O
examples	O
include	O
Group	O
Policy	O
,	O
Encrypting	O
File	O
System	O
,	O
BitLocker	O
,	O
Domain	B-Protocol
Name	I-Protocol
Services	I-Protocol
,	O
Remote	B-Protocol
Desktop	I-Protocol
Services	I-Protocol
,	O
Exchange	B-Operating_System
Server	I-Operating_System
and	O
SharePoint	B-Protocol
Server	I-Protocol
.	O
</s>
<s>
The	O
self-managed	O
Active	B-Protocol
Directory	I-Protocol
DS	O
must	O
not	O
be	O
confused	O
with	O
managed	O
Azure	B-Device
AD	I-Device
DS	I-Device
,	O
which	O
is	O
a	O
cloud	O
product	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Lightweight	O
Directory	O
Services	O
(	O
AD	O
LDS	O
)	O
,	O
formerly	O
known	O
as	O
Active	B-Protocol
Directory	I-Protocol
Application	O
Mode	O
(	O
ADAM	O
)	O
,	O
is	O
an	O
implementation	O
of	O
the	O
LDAP	B-Protocol
protocol	O
for	O
AD	B-Protocol
DS	I-Protocol
.	O
</s>
<s>
AD	O
LDS	O
runs	O
as	O
a	O
service	O
on	O
Windows	B-Device
Server	I-Device
.	O
</s>
<s>
AD	O
LDS	O
shares	O
the	O
code	O
base	O
with	O
AD	B-Protocol
DS	I-Protocol
and	O
provides	O
the	O
same	O
functionality	O
,	O
including	O
an	O
identical	O
API	B-General_Concept
,	O
but	O
does	O
not	O
require	O
the	O
creation	O
of	O
domains	O
or	O
domain	B-General_Concept
controllers	I-General_Concept
.	O
</s>
<s>
It	O
provides	O
a	O
Data	O
Store	O
for	O
the	O
storage	O
of	O
directory	O
data	O
and	O
a	O
Directory	O
Service	O
with	O
an	O
LDAP	B-Protocol
Directory	O
Service	O
Interface	O
.	O
</s>
<s>
Unlike	O
AD	B-Protocol
DS	I-Protocol
,	O
however	O
,	O
multiple	O
AD	O
LDS	O
instances	O
can	O
run	O
on	O
the	O
same	O
server	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Certificate	O
Services	O
(	O
AD	O
CS	O
)	O
establishes	O
an	O
on-premises	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
.	O
</s>
<s>
These	O
certificates	O
can	O
be	O
used	O
to	O
encrypt	O
files	O
(	O
when	O
used	O
with	O
Encrypting	O
File	O
System	O
)	O
,	O
emails	O
(	O
per	O
S/MIME	B-Protocol
standard	O
)	O
,	O
and	O
network	O
traffic	O
(	O
when	O
used	O
by	O
virtual	B-Application
private	I-Application
networks	I-Application
,	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
protocol	I-Protocol
or	O
IPSec	B-Protocol
protocol	O
)	O
.	O
</s>
<s>
AD	O
CS	O
predates	O
Windows	B-Device
Server	I-Device
2008	I-Device
,	O
but	O
its	O
name	O
was	O
simply	O
Certificate	O
Services	O
.	O
</s>
<s>
AD	O
CS	O
requires	O
an	O
AD	B-Protocol
DS	I-Protocol
infrastructure	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Federation	O
Services	O
(	O
AD	O
FS	O
)	O
is	O
a	O
single	O
sign-on	O
service	O
.	O
</s>
<s>
internet	B-Application
forum	I-Application
,	O
blog	O
,	O
online	O
shopping	O
,	O
webmail	B-Protocol
)	O
or	O
network	O
resources	O
using	O
only	O
one	O
set	O
of	O
credentials	O
stored	O
at	O
a	O
central	O
location	O
,	O
as	O
opposed	O
to	O
having	O
to	O
be	O
granted	O
a	O
dedicated	O
set	O
of	O
credentials	O
for	O
each	O
service	O
.	O
</s>
<s>
AD	O
FS	O
's	O
purpose	O
is	O
an	O
extension	O
of	O
that	O
of	O
AD	B-Protocol
DS	I-Protocol
:	O
The	O
latter	O
enables	O
users	O
to	O
authenticate	O
with	O
and	O
use	O
the	O
devices	O
that	O
are	O
part	O
of	O
the	O
same	O
network	O
,	O
using	O
one	O
set	O
of	O
credentials	O
.	O
</s>
<s>
AD	O
FS	O
requires	O
an	O
AD	B-Protocol
DS	I-Protocol
infrastructure	O
,	O
although	O
its	O
federation	O
partner	O
may	O
not	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Rights	O
Management	O
Services	O
(	O
AD	O
RMS	O
,	O
known	O
as	O
Rights	O
Management	O
Services	O
or	O
RMS	O
before	O
Windows	B-Device
Server	I-Device
2008	I-Device
)	O
is	O
a	O
server	O
software	O
for	O
information	O
rights	O
management	O
shipped	O
with	O
Windows	B-Device
Server	I-Device
.	O
</s>
<s>
It	O
uses	O
encryption	O
and	O
a	O
form	O
of	O
selective	O
functionality	O
denial	O
for	O
limiting	O
access	O
to	O
documents	O
such	O
as	O
corporate	O
e-mails	O
,	O
Microsoft	B-Application
Word	I-Application
documents	O
,	O
and	O
web	O
pages	O
,	O
and	O
the	O
operations	O
authorized	O
users	O
can	O
perform	O
on	O
them	O
.	O
</s>
<s>
As	O
a	O
directory	O
service	O
,	O
an	O
Active	B-Protocol
Directory	I-Protocol
instance	O
consists	O
of	O
a	O
database	O
and	O
corresponding	O
executable	B-Application
code	I-Application
responsible	O
for	O
servicing	O
requests	O
and	O
maintaining	O
the	O
database	O
.	O
</s>
<s>
The	O
executable	B-Application
part	O
,	O
known	O
as	O
Directory	O
System	O
Agent	O
,	O
is	O
a	O
collection	O
of	O
Windows	B-Application
services	O
and	O
processes	B-Operating_System
that	O
run	O
on	O
Windows	B-Application
2000	I-Application
and	O
later	O
.	O
</s>
<s>
Objects	O
in	O
Active	B-Protocol
Directory	I-Protocol
databases	O
can	O
be	O
accessed	O
via	O
LDAP	B-Protocol
,	O
ADSI	O
(	O
a	O
component	B-Application
object	I-Application
model	I-Application
interface	O
)	O
,	O
messaging	B-Protocol
API	I-Protocol
and	O
Security	O
Accounts	O
Manager	O
services	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
structures	O
are	O
arrangements	O
of	O
information	O
about	O
objects	O
.	O
</s>
<s>
The	O
objects	O
fall	O
into	O
two	O
broad	O
categories	O
:	O
resources	O
(	O
e.g.	O
,	O
printers	O
)	O
and	O
security	B-General_Concept
principals	I-General_Concept
(	O
user	O
or	O
computer	O
accounts	O
and	O
groups	O
)	O
.	O
</s>
<s>
Security	B-General_Concept
principals	I-General_Concept
are	O
assigned	O
unique	O
security	O
identifiers	O
(	O
SIDs	O
)	O
.	O
</s>
<s>
An	O
object	O
is	O
uniquely	O
identified	O
by	O
its	O
name	O
and	O
has	O
a	O
set	O
of	O
attributes	O
—	O
the	O
characteristics	O
and	O
information	O
that	O
the	O
object	O
represents	O
—	O
defined	O
by	O
a	O
schema	B-Application
,	O
which	O
also	O
determines	O
the	O
kinds	O
of	O
objects	O
that	O
can	O
be	O
stored	O
in	O
the	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
The	O
schema	B-Application
object	I-Application
lets	O
administrators	O
extend	O
or	O
modify	O
the	O
schema	B-Application
when	O
necessary	O
.	O
</s>
<s>
However	O
,	O
because	O
each	O
schema	B-Application
object	I-Application
is	O
integral	O
to	O
the	O
definition	O
of	O
Active	B-Protocol
Directory	I-Protocol
objects	I-Protocol
,	O
deactivating	O
or	O
changing	O
these	O
objects	O
can	O
fundamentally	O
change	O
or	O
disrupt	O
a	O
deployment	O
.	O
</s>
<s>
Schema	B-Application
changes	O
automatically	O
propagate	O
throughout	O
the	O
system	O
.	O
</s>
<s>
Changing	O
the	O
schema	B-Application
usually	O
requires	O
planning	O
.	O
</s>
<s>
The	O
Active	B-Protocol
Directory	I-Protocol
framework	O
that	O
holds	O
objects	O
can	O
be	O
viewed	O
at	O
a	O
number	O
of	O
levels	O
.	O
</s>
<s>
The	O
forest	O
,	O
tree	O
,	O
and	O
domain	O
are	O
the	O
logical	O
divisions	O
in	O
an	O
Active	B-Protocol
Directory	I-Protocol
network	O
.	O
</s>
<s>
Domains	O
are	O
identified	O
by	O
their	O
DNS	B-Protocol
name	I-Protocol
structure	O
,	O
the	O
namespace	O
.	O
</s>
<s>
A	O
domain	O
is	O
defined	O
as	O
a	O
logical	O
group	O
of	O
network	O
objects	O
(	O
computers	O
,	O
users	O
,	O
devices	O
)	O
that	O
share	O
the	O
same	O
Active	B-Protocol
Directory	I-Protocol
database	O
.	O
</s>
<s>
A	O
tree	O
is	O
a	O
collection	O
of	O
one	O
or	O
more	O
domains	O
and	O
domain	B-Protocol
trees	I-Protocol
in	O
a	O
contiguous	O
namespace	O
and	O
is	O
linked	O
in	O
a	O
transitive	O
trust	O
hierarchy	O
.	O
</s>
<s>
A	O
forest	O
is	O
a	O
collection	O
of	O
trees	O
that	O
share	O
a	O
common	O
global	B-Protocol
catalog	I-Protocol
,	O
directory	O
schema	B-Application
,	O
logical	O
structure	O
,	O
and	O
directory	O
configuration	O
.	O
</s>
<s>
The	O
objects	O
held	O
within	O
a	O
domain	O
can	O
be	O
grouped	O
into	O
organizational	B-Protocol
units	I-Protocol
(	O
OUs	O
)	O
.	O
</s>
<s>
The	O
OU	O
is	O
the	O
recommended	O
level	O
at	O
which	O
to	O
apply	O
group	O
policies	O
,	O
which	O
are	O
Active	B-Protocol
Directory	I-Protocol
objects	I-Protocol
formally	O
named	O
group	O
policy	O
objects	O
(	O
GPOs	B-General_Concept
)	O
,	O
although	O
policies	O
can	O
also	O
be	O
applied	O
to	O
domains	O
or	O
sites	O
(	O
see	O
below	O
)	O
.	O
</s>
<s>
Organizational	B-Protocol
units	I-Protocol
do	O
not	O
each	O
have	O
a	O
separate	O
namespace	O
.	O
</s>
<s>
As	O
a	O
consequence	O
,	O
for	O
compatibility	O
with	O
Legacy	O
NetBios	B-Protocol
implementations	O
,	O
user	O
accounts	O
with	O
an	O
identical	O
sAMAccountName	O
are	O
not	O
allowed	O
within	O
the	O
same	O
domain	O
even	O
if	O
the	O
accounts	O
objects	O
are	O
in	O
separate	O
OUs	O
.	O
</s>
<s>
In	O
general	O
,	O
the	O
reason	O
for	O
this	O
lack	O
of	O
allowance	O
for	O
duplicate	O
names	O
through	O
hierarchical	O
directory	O
placement	O
is	O
that	O
Microsoft	O
primarily	O
relies	O
on	O
the	O
principles	O
of	O
NetBIOS	B-Protocol
,	O
which	O
is	O
a	O
flat-namespace	O
method	O
of	O
network	O
object	O
management	O
that	O
,	O
for	O
Microsoft	O
software	O
,	O
goes	O
all	O
the	O
way	O
back	O
to	O
Windows	B-Device
NT	I-Device
3.1	I-Device
and	O
MS-DOS	B-Application
LAN	B-Algorithm
Manager	I-Algorithm
.	O
</s>
<s>
Allowing	O
for	O
duplication	O
of	O
object	O
names	O
in	O
the	O
directory	O
,	O
or	O
completely	O
removing	O
the	O
use	O
of	O
NetBIOS	B-Protocol
names	O
,	O
would	O
prevent	O
backward	O
compatibility	O
with	O
legacy	O
software	O
and	O
equipment	O
.	O
</s>
<s>
However	O
,	O
disallowing	O
duplicate	O
object	O
names	O
in	O
this	O
way	O
is	O
a	O
violation	O
of	O
the	O
LDAP	B-Protocol
RFCs	O
on	O
which	O
Active	B-Protocol
Directory	I-Protocol
is	O
supposedly	O
based	O
.	O
</s>
<s>
Alternatives	O
include	O
creating	O
a	O
separate	O
ID	O
system	O
of	O
unique	O
employee/student	O
ID	O
numbers	O
to	O
use	O
as	O
account	O
names	O
in	O
place	O
of	O
actual	O
users	O
 '	O
names	O
and	O
allowing	O
users	O
to	O
nominate	O
their	O
preferred	O
word	O
sequence	O
within	O
an	O
acceptable	B-Application
use	I-Application
policy	I-Application
.	O
</s>
<s>
In	O
Microsoft	O
's	O
Active	B-Protocol
Directory	I-Protocol
,	O
OUs	O
do	O
not	O
confer	O
access	O
permissions	O
,	O
and	O
objects	O
placed	O
within	O
OUs	O
are	O
not	O
automatically	O
assigned	O
access	O
privileges	O
based	O
on	O
their	O
containing	O
OU	O
.	O
</s>
<s>
This	O
is	O
a	O
design	O
limitation	O
specific	O
to	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
Other	O
competing	O
directories	O
such	O
as	O
Novell	B-Application
NDS	I-Application
can	O
assign	O
access	O
privileges	O
through	O
object	O
placement	O
within	O
an	O
OU	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
requires	O
a	O
separate	O
step	O
for	O
an	O
administrator	O
to	O
assign	O
an	O
object	O
in	O
an	O
OU	O
as	O
a	O
member	O
of	O
a	O
group	O
also	O
within	O
that	O
OU	O
.	O
</s>
<s>
A	O
common	O
workaround	O
for	O
an	O
Active	B-Protocol
Directory	I-Protocol
administrator	O
is	O
to	O
write	O
a	O
custom	O
PowerShell	B-Application
or	O
Visual	B-Application
Basic	I-Application
script	I-Application
to	O
automatically	O
create	O
and	O
maintain	O
a	O
user	O
group	O
for	O
each	O
OU	O
in	O
their	O
directory	O
.	O
</s>
<s>
Microsoft	O
refers	O
to	O
shadow	O
groups	O
in	O
the	O
Server	B-Device
2008	I-Device
Reference	O
documentation	O
but	O
does	O
not	O
explain	O
how	O
to	O
create	O
them	O
.	O
</s>
<s>
There	O
are	O
no	O
built-in	O
server	O
methods	O
or	O
console	O
snap-ins	B-Application
for	O
managing	O
shadow	O
groups	O
.	O
</s>
<s>
The	O
Active	B-Protocol
Directory	I-Protocol
database	O
is	O
organized	O
in	O
partitions	O
,	O
each	O
holding	O
specific	O
object	O
types	O
and	O
following	O
a	O
specific	O
replication	O
pattern	O
.	O
</s>
<s>
The	O
'	O
Schema	B-Application
 '	O
partition	O
contains	O
the	O
definition	O
of	O
object	O
classes	O
and	O
attributes	O
within	O
the	O
Forest	O
.	O
</s>
<s>
Sites	O
are	O
physical	O
(	O
rather	O
than	O
logical	O
)	O
groupings	O
defined	O
by	O
one	O
or	O
more	O
IP	B-Protocol
subnets	O
.	O
</s>
<s>
AD	O
also	O
holds	O
the	O
definitions	O
of	O
connections	O
,	O
distinguishing	O
low-speed	O
(	O
e.g.	O
,	O
WAN	O
,	O
VPN	B-Application
)	O
from	O
high-speed	O
(	O
e.g.	O
,	O
LAN	B-General_Concept
)	O
links	O
.	O
</s>
<s>
Sites	O
are	O
used	O
to	O
control	O
network	O
traffic	O
generated	O
by	O
replication	O
and	O
also	O
to	O
refer	O
clients	O
to	O
the	O
nearest	O
domain	B-General_Concept
controllers	I-General_Concept
(	O
DCs	O
)	O
.	O
</s>
<s>
Microsoft	B-Operating_System
Exchange	I-Operating_System
Server	I-Operating_System
2007	I-Operating_System
uses	O
the	O
site	O
topology	O
for	O
mail	O
routing	O
.	O
</s>
<s>
Physically	O
,	O
the	O
Active	B-Protocol
Directory	I-Protocol
information	O
is	O
held	O
on	O
one	O
or	O
more	O
peer	O
domain	B-General_Concept
controllers	I-General_Concept
,	O
replacing	O
the	O
NT	B-Device
PDC/BDC	O
model	O
.	O
</s>
<s>
Each	O
DC	O
has	O
a	O
copy	O
of	O
the	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
Servers	O
joined	O
to	O
Active	B-Protocol
Directory	I-Protocol
that	O
is	O
not	O
domain	B-General_Concept
controllers	I-General_Concept
are	O
called	O
Member	O
Servers	O
.	O
</s>
<s>
A	O
subset	O
of	O
objects	O
in	O
the	O
domain	O
partition	O
replicate	O
to	O
domain	B-General_Concept
controllers	I-General_Concept
that	O
are	O
configured	O
as	O
global	B-Protocol
catalogs	I-Protocol
.	O
</s>
<s>
Global	B-Protocol
catalog	I-Protocol
(	O
GC	O
)	O
servers	O
provide	O
a	O
global	O
listing	O
of	O
all	O
objects	O
in	O
the	O
Forest	O
.	O
</s>
<s>
Global	B-Protocol
Catalog	I-Protocol
servers	O
replicate	O
to	O
themselves	O
all	O
objects	O
from	O
all	O
domains	O
and	O
,	O
hence	O
,	O
provide	O
a	O
global	O
listing	O
of	O
objects	O
in	O
the	O
forest	O
.	O
</s>
<s>
The	O
PAS	O
can	O
be	O
modified	O
by	O
modifying	O
the	O
schema	B-Application
and	O
marking	O
attributes	O
for	O
replication	O
to	O
the	O
GC	O
.	O
</s>
<s>
Earlier	O
versions	O
of	O
Windows	B-Application
used	O
NetBIOS	B-Protocol
to	O
communicate	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
is	O
fully	O
integrated	O
with	O
DNS	B-Protocol
and	O
requires	O
TCP/IP	B-Protocol
—	O
DNS	B-Protocol
.	O
</s>
<s>
To	O
be	O
fully	O
functional	O
,	O
the	O
DNS	B-Protocol
server	O
must	O
support	O
SRV	B-Protocol
resource	I-Protocol
records	I-Protocol
,	O
also	O
known	O
as	O
service	O
records	O
.	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
synchronizes	O
changes	O
using	O
multi-master	B-Operating_System
replication	I-Operating_System
.	O
</s>
<s>
Each	O
link	O
can	O
have	O
a	O
'	O
cost	O
 '	O
(	O
e.g.	O
,	O
DS3	O
,	O
T1	B-Protocol
,	O
ISDN	B-Protocol
,	O
etc	O
.	O
)	O
</s>
<s>
Replication	O
for	O
Active	B-Protocol
Directory	I-Protocol
zones	O
is	O
automatically	O
configured	O
when	O
DNS	B-Protocol
is	O
activated	O
in	O
the	O
domain-based	O
by	O
the	O
site	O
.	O
</s>
<s>
Replication	O
of	O
Active	B-Protocol
Directory	I-Protocol
uses	O
Remote	B-Operating_System
Procedure	I-Operating_System
Calls	I-Operating_System
(	O
RPC	O
)	O
over	O
IP	B-Protocol
(	O
RPC/IP	O
)	O
.	O
</s>
<s>
Between	O
Sites	O
,	O
SMTP	B-Protocol
can	O
be	O
used	O
for	O
replication	O
,	O
but	O
only	O
for	O
changes	O
in	O
the	O
Schema	B-Application
,	O
Configuration	O
,	O
or	O
Partial	O
Attribute	O
Set	O
(	O
Global	B-Protocol
Catalog	I-Protocol
)	O
GCs	O
.	O
</s>
<s>
SMTP	B-Protocol
cannot	O
be	O
used	O
for	O
replicating	O
the	O
default	O
Domain	O
partition	O
.	O
</s>
<s>
In	O
general	O
,	O
a	O
network	O
utilizing	O
Active	B-Protocol
Directory	I-Protocol
has	O
more	O
than	O
one	O
licensed	O
Windows	B-Device
server	I-Device
computer	O
.	O
</s>
<s>
Backup	O
and	O
restore	O
of	O
Active	B-Protocol
Directory	I-Protocol
is	O
possible	O
for	O
a	O
network	O
with	O
a	O
single	O
domain	B-General_Concept
controller	I-General_Concept
,	O
but	O
Microsoft	O
recommends	O
more	O
than	O
one	O
domain	B-General_Concept
controller	I-General_Concept
to	O
provide	O
automatic	O
failover	B-General_Concept
protection	O
of	O
the	O
directory	O
.	O
</s>
<s>
Domain	B-General_Concept
controllers	I-General_Concept
are	O
also	O
ideally	O
single-purpose	O
for	O
directory	O
operations	O
only	O
,	O
and	O
should	O
not	O
run	O
any	O
other	O
software	O
or	O
role	O
.	O
</s>
<s>
Certain	O
Microsoft	O
products	O
such	O
as	O
SQL	O
Server	O
and	O
Exchange	O
can	O
interfere	O
with	O
the	O
operation	O
of	O
a	O
domain	B-General_Concept
controller	I-General_Concept
,	O
necessitating	O
isolation	O
of	O
these	O
products	O
on	O
additional	O
Windows	B-Device
servers	I-Device
.	O
</s>
<s>
Combining	O
them	O
can	O
make	O
configuration	O
or	O
troubleshooting	O
of	O
either	O
the	O
domain	B-General_Concept
controller	I-General_Concept
or	O
the	O
other	O
installed	O
software	O
more	O
difficult	O
.	O
</s>
<s>
A	O
business	O
intending	O
to	O
implement	O
Active	B-Protocol
Directory	I-Protocol
is	O
therefore	O
recommended	O
to	O
purchase	O
a	O
number	O
of	O
Windows	B-Device
server	I-Device
licenses	O
,	O
to	O
provide	O
for	O
at	O
least	O
two	O
separate	O
domain	B-General_Concept
controllers	I-General_Concept
,	O
and	O
optionally	O
,	O
additional	O
domain	B-General_Concept
controllers	I-General_Concept
for	O
performance	O
or	O
redundancy	O
,	O
a	O
separate	O
file	O
server	O
,	O
a	O
separate	O
Exchange	B-Operating_System
server	I-Operating_System
,	O
a	O
separate	O
SQL	O
Server	O
,	O
and	O
so	O
forth	O
to	O
support	O
the	O
various	O
server	O
roles	O
.	O
</s>
<s>
Physical	O
hardware	O
costs	O
for	O
the	O
many	O
separate	O
servers	O
can	O
be	O
reduced	O
through	O
the	O
use	O
of	O
virtualization	B-General_Concept
,	O
although	O
for	O
proper	O
failover	B-General_Concept
protection	O
,	O
Microsoft	O
recommends	O
not	O
running	O
multiple	O
virtualized	B-General_Concept
domain	B-General_Concept
controllers	I-General_Concept
on	O
the	O
same	O
physical	O
hardware	O
.	O
</s>
<s>
The	O
Active-Directory	O
database	O
,	O
the	O
directory	O
store	O
,	O
in	O
Windows	B-Application
2000	I-Application
Server	O
uses	O
the	O
JET	O
Blue-based	O
Extensible	B-Application
Storage	I-Application
Engine	I-Application
(	O
ESE98	O
)	O
and	O
is	O
limited	O
to	O
16	O
terabytes	O
and	O
2	O
billion	O
objects	O
(	O
but	O
only	O
1	O
billion	O
security	B-General_Concept
principals	I-General_Concept
)	O
in	O
each	O
domain	B-General_Concept
controller	I-General_Concept
's	O
database	O
.	O
</s>
<s>
Windows	B-Application
Server	I-Application
2003	I-Application
added	O
a	O
third	O
main	O
table	O
for	O
security	O
descriptor	O
single	O
instancing	O
.	O
</s>
<s>
Programs	O
may	O
access	O
the	O
features	O
of	O
Active	B-Protocol
Directory	I-Protocol
via	O
the	O
COM	B-Application
interfaces	I-Application
provided	O
by	O
Active	B-Protocol
Directory	I-Protocol
Service	I-Protocol
Interfaces	I-Protocol
.	O
</s>
<s>
To	O
allow	O
users	O
in	O
one	O
domain	O
to	O
access	O
resources	O
in	O
another	O
,	O
Active	B-Protocol
Directory	I-Protocol
uses	O
trusts	O
.	O
</s>
<s>
A	O
one-way	O
trust	O
used	O
by	O
Microsoft	O
Identity	O
Manager	O
from	O
a	O
(	O
possibly	O
low-level	O
)	O
production	O
forest	O
to	O
a	O
(	O
Windows	B-Device
Server	I-Device
2016	I-Device
functionality	O
level	O
)	O
'	O
bastion	O
 '	O
forest	O
,	O
which	O
issues	O
time-limited	O
group	O
memberships	O
.	O
</s>
<s>
Microsoft	B-Protocol
Active	I-Protocol
Directory	I-Protocol
management	O
tools	O
include	O
:	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Administrative	O
Center	O
(	O
Introduced	O
with	O
Windows	B-Device
Server	I-Device
2012	O
and	O
above	O
)	O
,	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Users	O
and	O
Computers	O
,	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Domains	O
and	O
Trusts	O
,	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Sites	O
and	O
Services	O
,	O
</s>
<s>
Active	B-Protocol
Directory	I-Protocol
Schema	I-Protocol
snap-ins	B-Application
for	O
Microsoft	B-Application
Management	I-Application
Console	I-Application
(	O
MMC	O
)	O
,	O
</s>
<s>
Varying	O
levels	O
of	O
interoperability	O
with	O
Active	B-Protocol
Directory	I-Protocol
can	O
be	O
achieved	O
on	O
most	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
including	O
Unix	B-Application
,	O
Linux	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
or	O
Java	O
and	O
Unix-based	O
programs	O
)	O
through	O
standards-compliant	O
LDAP	B-Protocol
clients	O
,	O
but	O
these	O
systems	O
usually	O
do	O
not	O
interpret	O
many	O
attributes	O
associated	O
with	O
Windows	B-Application
components	O
,	O
such	O
as	O
Group	O
Policy	O
and	O
support	O
for	O
one-way	O
trusts	O
.	O
</s>
<s>
Third	O
parties	O
offer	O
Active	B-Protocol
Directory	I-Protocol
integration	O
for	O
Unix-like	B-Operating_System
platforms	O
,	O
including	O
:	O
</s>
<s>
The	O
schema	B-Application
additions	O
shipped	O
with	O
Windows	B-Application
Server	I-Application
2003	I-Application
R2	O
include	O
attributes	O
that	O
map	O
closely	O
enough	O
to	O
RFC	O
2307	O
to	O
be	O
generally	O
usable	O
.	O
</s>
<s>
The	O
default	O
schema	B-Application
for	O
group	O
membership	O
complies	O
with	O
RFC	O
2307bis	O
(	O
proposed	O
)	O
.	O
</s>
<s>
Windows	B-Application
Server	I-Application
2003	I-Application
R2	O
includes	O
a	O
Microsoft	B-Application
Management	I-Application
Console	I-Application
snap-in	O
that	O
creates	O
and	O
edits	O
the	O
attributes	O
.	O
</s>
<s>
An	O
alternative	O
option	O
is	O
to	O
use	O
another	O
directory	O
service	O
as	O
non-Windows	O
clients	O
authenticate	O
to	O
this	O
while	O
Windows	B-Application
Clients	O
authenticate	O
to	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
Non-Windows	O
clients	O
include	O
389	O
Directory	O
Server	O
(	O
formerly	O
Fedora	O
Directory	O
Server	O
,	O
FDS	O
)	O
,	O
ViewDS	O
v7.2	O
XML	B-Protocol
Enabled	I-Protocol
Directory	I-Protocol
,	O
and	O
Sun	O
Microsystems	O
Sun	B-Application
Java	I-Application
System	I-Application
Directory	I-Application
Server	I-Application
.	O
</s>
<s>
The	O
latter	O
two	O
are	O
both	O
able	O
to	O
perform	O
two-way	O
synchronization	O
with	O
Active	B-Protocol
Directory	I-Protocol
and	O
thus	O
provide	O
a	O
"	O
deflected	O
"	O
integration	O
.	O
</s>
<s>
Another	O
option	O
is	O
to	O
use	O
OpenLDAP	B-Language
with	O
its	O
translucent	O
overlay	O
,	O
which	O
can	O
extend	O
entries	O
in	O
any	O
remote	O
LDAP	B-Protocol
server	O
with	O
additional	O
attributes	O
stored	O
in	O
a	O
local	O
database	O
.	O
</s>
<s>
Administration	O
(	O
querying	O
,	O
modifying	O
,	O
and	O
monitoring	O
)	O
of	O
Active	B-Protocol
Directory	I-Protocol
can	O
be	O
achieved	O
via	O
many	O
scripting	O
languages	O
,	O
including	O
PowerShell	B-Application
,	O
VBScript	B-Application
,	O
JScript/JavaScript	B-Language
,	O
Perl	B-Language
,	O
Python	B-Language
,	O
and	O
Ruby	B-Language
.	O
</s>
<s>
Free	O
and	O
non-free	O
Active	B-Protocol
Directory	I-Protocol
administration	O
tools	O
can	O
help	O
to	O
simplify	O
and	O
possibly	O
automate	O
Active	B-Protocol
Directory	I-Protocol
management	O
tasks	O
.	O
</s>
<s>
Since	O
October	O
2017	O
Amazon	B-Application
AWS	I-Application
offers	O
integration	O
with	O
Microsoft	B-Protocol
Active	I-Protocol
Directory	I-Protocol
.	O
</s>
