<s>
The	O
NTP	B-Protocol
pool	I-Protocol
is	O
a	O
dynamic	O
collection	O
of	O
networked	O
computers	O
that	O
volunteer	O
to	O
provide	O
highly	O
accurate	O
time	O
via	O
the	O
Network	B-Protocol
Time	I-Protocol
Protocol	I-Protocol
to	O
clients	O
worldwide	O
.	O
</s>
<s>
The	O
machines	O
that	O
are	O
"	O
in	O
the	O
pool	O
"	O
are	O
part	O
of	O
the	O
pool.ntp.org	B-Protocol
domain	B-Protocol
as	O
well	O
as	O
of	O
several	O
subdomains	B-Protocol
divided	O
by	O
geographical	O
zone	O
and	O
are	O
distributed	O
to	O
NTP	O
clients	O
via	O
round	B-Protocol
robin	I-Protocol
DNS	I-Protocol
.	O
</s>
<s>
Work	O
is	O
being	O
done	O
to	O
make	O
the	O
geographic	O
zone	O
selection	O
unnecessary	O
,	O
via	O
customized	O
authoritative	O
DNS	B-Protocol
servers	O
that	O
utilize	O
geolocation	B-Application
software	I-Application
.	O
</s>
<s>
the	O
pool	O
consists	O
of	O
3,126	O
active	O
time	O
servers	O
on	O
IPv4	B-Protocol
and	O
1,534	O
servers	O
on	O
IPv6	B-Protocol
.	O
</s>
<s>
Joining	O
the	O
pool	O
requires	O
at	O
least	O
a	O
broadband	B-General_Concept
connection	O
to	O
the	O
Internet	O
,	O
a	O
static	O
IP	B-Protocol
address	I-Protocol
,	O
and	O
accurate	O
time	O
from	O
another	O
source	O
(	O
for	O
example	O
another	O
NTP	B-Protocol
server	I-Protocol
,	O
from	O
a	O
DCF77	O
receiver	O
,	O
WWVB	O
receiver	O
or	O
a	O
GPS	O
receiver	O
)	O
.	O
</s>
