In my previous article Configure NTP on an ESXi Host I explained you how you can configure your ESXi host to synchronize clock from NTP servers but it can never be easy things do break problems do occur. IT industry is not like roaming in wonderland hence it becomes more important to troubleshoot thing rather than to configure things.
1. ) The first option for troubleshooting is checking the NTP server. If you have the NTP server on your local network and your firewall allows ping then you can try to see if you can ping it.
2.) Second option is to use the NTPQ utility. It is the NTP query program installed in almost all the Linux programs. You can find the information about the ntqp program from here
The ESXi shell has ntpq utility you can use ntpq -p to query the status of the NTP synchornization
If you see the error ” No association IDs returned” Then it means the ESXi has not synchronized with the NTP server.
3.) To troubleshoot further you can read the log messages in /var/log/
type the command
I am using ESXi 5 so path to the log file is /var/log/syslog.log
You can see the screenshot here
4.) The fourth problem can be DNS or routing. If your DNS and default gateways are not configured properly then you might not be able to synchronize with the NTP server as request wont be able to reach the NTP servers.
NOTE :- It takes 5-10 minutes to synchronize to internet time servers, wait before you perform any kind of troubleshooting.
You can also refer this VmwarekB Article