date 또는 timedatectl
sudo yum erase 'ntp*'
sudo yum install chrony
vi /etc/chrony.conf
server 169.254.169.123 prefer iburst minpoll 4 maxpoll 4 # pool 문 아래에 해당 라인 추가
sudo service chronyd restart
sudo chkconfig chronyd on
chronyc sources -v
timedatectl set-timezone Asia/Seoul