NTP服务器和客户端的设置及使用(EN版)
# 17 datum GPS_DATUM Datum Precision Time System
# 18 acts NIST_ACTS NIST Automated Computer Time Service
# 19 heath WWV_HEATH Heath WWV/WWVH Receiver
# 20 nmea GPS_NMEA Generic NMEA GPS Receiver
# 22 pps ATOM_PPS PPS Clock Discipline
# 23 ptbacts PTB_ACTS PTB Automated Computer Time Service
#
# Some of the devices benefit from "fudge" factors. See the xntpd
# documentation.
# Either a peer or server. Replace "XType" with a value from the
# table above.
#If you are adding a local hardware clock device,
#its driver is identified here by a directive like: server
#127.127.XX.0 where 127.127 alerts NTP that this is a local rather
#than a remote network peer, and XX is a clocktype described in
#the NTP distribution. The restrict directive in this config file
#specifies that this host will only talk to the two IP addresses
#specified; it won't trust anyone else, and it won't serve time
#to anyone else.
#following three lines are there by default, change them according
to your own setup.
server 127.127.XType.0 prefer
fudge 127.127.XType.0 stratum 0
broadcast 224.0.1.1 ttl 4
#three types of time servers
# 1. peer host_address [ key # ] [ version # ] [ prefer ]
# Specifies that local server is to operate in symmetric
active mode with
# remote server specified as host_address, i.e.
# local server can be synchronized to the remote server
# 2. server host_address [ key # ] [ version # ] [ prefer ] [ mode]
server
# Specifies that the local server is to operate in
# "client" mode with the remote server named in the com-
# mand. In this mode the local server can be synchronized
# to the remote server, but the remote server can never
# be synchronized to the local server.
# 3. broadcast host_address [ key # ] [ version # ] [ttl # ]
# Specifies that the local server is to operate in
# "broadcast" mode where the local server sends periodic
# broadcast messages to a client population at the | 
