<s>
Inter-domain	B-Architecture
routing	I-Architecture
is	O
data	O
flow	O
control	O
and	O
interaction	O
between	O
Primary	B-General_Concept
Domain	I-General_Concept
Controller	I-General_Concept
(	O
PDC	B-General_Concept
)	O
computers	O
.	O
</s>
<s>
The	O
number	O
for	O
each	O
ISP	O
is	O
stored	O
within	O
a	O
DNS	B-Protocol
server	O
.	O
</s>
<s>
The	O
DNS	B-Protocol
servers	O
interpret	O
the	O
ISP	O
URL	O
Domain	O
name	O
and	O
provide	O
the	O
appropriate	O
IP	B-Protocol
address	I-Protocol
number	O
.	O
</s>
<s>
The	O
Domain	O
is	O
under	O
the	O
control	O
of	O
a	O
specialized	O
computer	O
,	O
called	O
a	O
PDC	B-General_Concept
,	O
(	O
primary	B-General_Concept
domain	I-General_Concept
controller	I-General_Concept
)	O
.	O
</s>
<s>
This	O
PDC	B-General_Concept
is	O
backed	O
up	O
by	O
an	O
SDC	O
,	O
(	O
a	O
secondary	O
domain	B-General_Concept
controller	I-General_Concept
)	O
,	O
this	O
computer	O
synchronises	O
itself	O
with	O
the	O
PDC	B-General_Concept
and	O
takes	O
over	O
the	O
role	O
in	O
the	O
event	O
of	O
a	O
PDC	B-General_Concept
failure	O
.	O
</s>
<s>
Multiple	O
replication	B-Architecture
servers	O
connect	O
to	O
these	O
control	O
computers	O
and	O
they	O
are	O
routed	O
to	O
the	O
Internet	B-General_Concept
backbone	I-General_Concept
to	O
provide	O
the	O
requested	O
data	O
to	O
and	O
from	O
the	O
domain	O
.	O
</s>
<s>
Internet	O
protocols	O
that	O
are	O
focused	O
on	O
inter-domain	B-Architecture
functions	O
include	O
:	O
Border	B-Protocol
Gateway	I-Protocol
Multicast	I-Protocol
Protocol	I-Protocol
,	O
Classless	B-Protocol
Inter-Domain	I-Protocol
Routing	I-Protocol
,	O
Multicast	B-Protocol
Source	I-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
,	O
and	O
Protocol	B-Protocol
Independent	I-Protocol
Multicast	I-Protocol
.	O
</s>
<s>
A	O
PDC	B-General_Concept
uses	O
a	O
number	O
of	O
special	O
computer	B-Application
programs	I-Application
to	O
announce	O
its	O
presence	O
to	O
other	O
domain	B-General_Concept
controllers	I-General_Concept
.	O
</s>
<s>
It	O
uses	O
Windows	B-Device
Internet	I-Device
naming	I-Device
service	I-Device
WINS	B-Device
and	O
Browser	B-Application
services	O
to	O
allow	O
other	O
computers	O
to	O
gain	O
access	O
to	O
digital	B-General_Concept
information	I-General_Concept
that	O
it	O
has	O
control	O
over	O
.	O
</s>
<s>
The	O
opposite	O
of	O
inter-domain	B-Architecture
routing	I-Architecture
is	O
intra-domain	B-Architecture
routing	I-Architecture
,	O
routing	O
within	O
a	O
domain	O
or	O
an	O
autonomous	B-Architecture
system	I-Architecture
.	O
</s>
