CentOS 7, 配置过ntpd与某个时间服务器同步后，偶然发现某一个节点的NTP synchronized一直是no:

# timedatectl

Local time: 二 2019-07-30 09:41:08 CST

Universal time: 二 2019-07-30 01:41:08 UTC

RTC time: 二 2019-07-30 01:08:13

Time zone: Asia/Shanghai (CST, +0800)

NTP enabled: yes

NTP synchronized: no

RTC in local TZ: no

DST active: n/a

停掉ntpd, 执行ntpd -gq重新调整时间后，再启动ntpd:

# systemctl stop ntpd

# ntpd -gq

ntpd: time slew +0.000041s

# systemctl start ntpd

等待一会儿后,NTP synchronized恢复成yes:

# timedatectl

Local time: 二 2019-07-30 09:44:28 CST

Universal time: 二 2019-07-30 01:44:28 UTC

RTC time: 二 2019-07-30 01:44:28

Time zone: Asia/Shanghai (CST, +0800)

NTP enabled: yes

NTP synchronized: yes

RTC in local TZ: no

DST active: n/a