Ntpd Crash

Hi Guys

every day i have this strange problem, our NTPD.SERVICE crash and the date on server does forward one hour .
npt is properly configured, what could be the cause? . I have the same problem on 4 servers.

service ntpd status
Redirecting to /bin/systemctl status ntpd.service
● ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2016-07-14 06:59:39 CEST; 3h 45m in ago
Process: 16601 ExecStart=/usr/sbin/ntpd -u ntp:ntp $OPTIONS (code=exited, stat us=0/SUCCESS)
Main PID: 16602 (code=exited, status=255)

Jul 13 09:54:33 frontend01 ntpd[16602]: 0.0.0.0 c61c 0c clock_step -35...s
Jul 13 08:55:07 frontend01 ntpd[16602]: 0.0.0.0 c614 04 freq_mode
Jul 13 08:55:08 frontend01 ntpd[16602]: 0.0.0.0 c618 08 no_sys_peer
Jul 13 09:10:49 frontend01 ntpd[16602]: 0.0.0.0 c612 02 freq_set kerne...M
Jul 13 09:10:49 frontend01 ntpd[16602]: 0.0.0.0 c615 05 clock_sync
Jul 14 04:56:15 frontend01 ntpd[16602]: 0.0.0.0 0618 08 no_sys_peer
Jul 14 06:59:39 frontend01 ntpd[16602]: 0.0.0.0 0617 07 panic_stop -35....
Jul 14 06:59:39 frontend01 systemd[1]: ntpd.service: main process exit...a
Jul 14 06:59:39 frontend01 systemd[1]: Unit ntpd.service entered faile....
Jul 14 06:59:39 frontend01 systemd[1]: ntpd.service failed.
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