集羣情況：
三臺機器分別：
master：180.201.163.46
slave1：180.201.156.76
slave2：180.201.130.17
網關：255.255.192.0
在slave1配置ntpserver，在master和slave2上配置ntpclient。
1、檢查ntp軟件包是否安裝
# rpm -qa | grep ntp
ntp-4.2.4p8-3.el6.centos.x86_64
# yum -y install ntp --如果沒有安裝需要安裝ntp
2、修改slave1上的ntp配置文件（ntpserver）
# vi /etc/ntp.conf，如下
For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).
driftfile /var/lib/ntp/drift
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery
# Permit all access over the loopback interface. This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict ::1
# Hosts on local network are less restricted.
restrict 180.201.0.0 mask 255.255.192.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 210.72.145.44 iburst prefer
server 202.112.10.36 iburst
server 59.124.196.83 iburst
restrict 210.72.145.44 modify notrap noquery
restrict 202.112.10.36 modify notrap noquery
restrict 59.124.196.83 modify notrap noquery
server 127.127.1.0
fudge 127.127.1.0 stratum 10
#broadcast 192.168.1.255 autokey # broadcast server
#broadcastclient # broadcast client
#broadcast 224.0.1.1 autokey # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 autokey # manycast client
# Enable public key cryptography.
#crypto
includefile /etc/ntp/crypto/pw
# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys
# Specify the key identifiers which are trusted.
#trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
#requestkey 8
# Specify the key identifier to use with the ntpq utility.
#controlkey 8
# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats
# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor
介紹請見
3、修改master和slave2上的ntp配置文件（ntpclient）
# vi /etc/ntp.conf，如下
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).
driftfile /var/lib/ntp/drift
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery
# Permit all access over the loopback interface. This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict ::1
# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server slave1 iburst
restrict slave1 mask nomodify notrap noquery
server 127.127.1.0
fudge 127.127.1.0 stratum 10
#broadcast 192.168.1.255 autokey # broadcast server
#broadcastclient # broadcast client
#broadcast 224.0.1.1 autokey # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 autokey # manycast client
# Enable public key cryptography.
#crypto
includefile /etc/ntp/crypto/pw
# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys
# Specify the key identifiers which are trusted.
#trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
#requestkey 8
# Specify the key identifier to use with the ntpq utility.
#controlkey 8
# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats
# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor
介紹如下：
4、啓動
# service ntpd start -- 啓動ntp
# chkconfig ntpd on --開機啓動
# service ntpd status --查看狀態
# ntpstat查看同步情況，如下則表示啓動成功
synchronised to NTP server (85.199.214.101) at stratum 2
time correct to within 155 ms
polling server every 64 s