Cannot set NTP in vCenter server

Products

VMware vCenter Server

Issue/Introduction

Configuring NTP server from VAMI on the vCenter server fails.

Basic connectivity exists between the vCenter server and the NTP server :

^{> A ping or traceroute command to check network connectivity to the NTP server is successful}
^{# ping <NTP_Server_IP_or_Hostname>}
^{# traceroute <NTP_Server_IP_or_Hostname>

> No firewall or network security device blocking UDP port 123, which is used for NTP communication}
^{# nc -uz <NTP_Server_IP_or_Hostname> 123}
^{# tcpdump -i <interface> udp port 123}

/var/log/vmware/applmgmt/applmgmt.log:

^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.impl:Operation output = b'\xe2\x97\x8f ntpd.service - Network Time Service\n}
^{Loaded: loaded (/usr/lib/systemd/system/ntpd.service; disabled; vendor preset: disabled)\n}
^{Active: active (running) since}
^{<date> hh:mm:ss   ntpd[3038432]: Listen and drop on 0 :123\n}
^{<date> hh:mm:ss   ntpd[3038432]: Listen and drop on 1 :123\n}
^{<date> hh:mm:ss   ntpd[3038432]: Listen normally on 2 :123\n}
^{<date> hh:mm:ss   ntpd[3038432]: Listen normally on 3 :123\n}
^{<date> hh:mm:ss   ntpd[3038432]: Listening on routing socket on fd #20 for interface updates\n}
^{<date> hh:mm:ss   ntpd[3038432]: kernel reports TIME_ERROR: 0x2041: Clock Unsynchronized\n}
^{<date> hh:mm:ss   ntpd[3038432]: kernel reports TIME_ERROR: 0x2041: Clock Unsynchronized\n <date> hh:mm:ss <NTP_Server_IP_or_Hostname> systemd[1]: Started Network Time Service.\n',}
^{error = b'' returncode = 0}

^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.impl:NTP status Up}
^{yyyy-mm-ddThh:mm:ss INFO:vmware.appliance.vapi.auth:Authorization request for service_id: com.vmware.appliance.ntp, operation_id: get}
^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.vherd.base.authorization_local:Verify privileges user (root) privilege ['ViewConfiguration']}
^{yyyy-mm-ddThh:mm:ss DEBUG:root:Validated user privileges in localstore or SSO}

^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.impl:com.vmware.appliance.ntp.get()}
^{yyyy-mm-ddThh:mm:ss INFO:vmware.appliance.vapi.auth:Authorization request for service_id: com.vmware.appliance.ntp, operation_id: test}

^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.impl:com.vmware.appliance.ntp.test(['<NTP_Server_IP_or_Hostname>'])}
^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.ntpTestUtils:Testing connection to: ['<NTP_Server_IP_or_Hostname>']}
^{yyyy-mm-ddThh:mm:ss DEBUG:vmware.appliance.timesync.ntpTestUtils:NTP test out: b'server <NTP_Server_IP>, stratum 1, offset , delay \n', err: b' <date> hh:mm:ss ntpdate[]: no server suitable for synchronization found\n', returncode: 1}
^{yyyy-mm-ddThh:mm:ss DEBUG:root:TestRunStatuses: servers=['<NTP_Server_IP_or_Hostname>'] statuses=['SERVER_UNREACHABLE']}

Running the command ntpdate -q <NTP_Server_IP_or_Hostname> returns the error: 'Server dropped: Server has gone too long without sync.' Additionally, the reference and originate timestamps in the output are significantly out of sync, indicating that the NTP server is not properly synchronized.

^{ntpdate -d}
^{<date> <time> ntpdate[]: ntpdate}
^{Looking for host <NTP_Server_IP_or_Hostname> and service ntp}
^{<NTP_Server_IP> reversed <NTP_Server_IP_or_Hostname>}
^{host found :}
^{transmit(<NTP_Server_IP>)}
^{receive(<NTP_Server_IP>)}
^{transmit(<NTP_Server_IP>)}
^{receive(<NTP_Server_IP>)}

^{server <NTP_Server_IP>, port 123}
^{stratum xx, precision xx, leap xx, trust xx}

^{reference time:       <date> <year> <time>}
^{originate timestamp:  <date> <year> <time>}
^{transmit timestamp:   <date> <year> <time>

<NTP_Server_IP>: Server dropped: server has gone too long without sync
...
...
<date> <year> <time> ntpdate[]: no server suitable for synchronization found}

Environment

vCenter Server 8.x

vCenter Server 7.x

Cause

Configuration issues on the NTP server, where the server's time is significantly out of sync with the actual time.

Resolution

Ensure that the NTP server's clock is properly synchronized, as any significant time discrepancy may prevent the vCenter Server from successfully completing the NTP synchronization process.

Additional Information

For more details - Troubleshooting NTP on ESX and ESXi 6.x / 7.x / 8.x