Fellow armv7-without-rtc-battery users. Maybe you have already learned this, but I THINK I have completed my education on this thanks to Miroslav Lichvar on the Chrony list. There are two issues here: It takes time for chronyd to set the system time. And if it fails to reach the ntp servers, well, it failed to set the time. For the first, we need to delay some services from starting until chronyd is successful. Postfix is one of them. So we need the following commands: systemctl enable chrony-wait systemctl start chrony-wait sed -i '/^After=/ s/$/ time-sync.target/w /dev/stdout' /usr/lib/systemd/system/postfix.service There are some possible instances where you also want to do this to httpd.service, but I have been advised on the postfix list NOT to run postfix if the systemtime is earlier than the postfix build date $ postconf -dh mail_release_date 20130622 Plus the postfix.service runs aliases.db which will mess up your aliases.db timestamp. Next there is that pesky issue about what if no ntp servers reached? First: cat <<EOF>/etc/sysconfig/chronyd || exit 1 OPTIONS=" -s" EOF Since Centos7 has Chronyd 2.1.1, not 2.2, we have extra work to do in chronyd.conf: cat <<EOF>>/etc/chrony.conf || exit 1 rtcdevice /dev/doesnotexist EOF I am adding this to my basic server howto page.