[$] The NTP pool system
NTP, the Network Time Protocol, quietly
and without much fuss performs the critical internet function of knowing
the correct time. Using it, a computer with imperfect communications links
may join a distributed community of servers, each of which is either
directly attached to a reliable clock, or is trying to best synchronize its
clock to one or more better-synchronized members of the community. The NTP
pool system has arisen as a method of providing such a community to the
internet; it works well, but is not without its challenges.