1 Reply Latest reply on Sep 6, 2014 1:50 AM by jlanders

    ESXi 5.5 NTP Client not getting sync

    kopper27 Expert

      hi guys


      I've followed this guide - VMware KB: Synchronizing ESXi/ESX time with a Microsoft Domain Controller -


      I already use this windows AD server to sync network devices just some of them (Network IO modules from Blade Centers not Big Guys) so I know it works and provides NTP Services.


      But it won't work for my ESXi Servers

      I get this

      ntpq -p timed out, nothing received

      ***Request timed out


      NTP client is up and running, there is not firewall in between, ssh is running.

      I followed this guide but it won't work, the only thing I don't have is synchronization with external NTP Server so I did not setup step 3

      so NTPServer Value under Parameters is itself



      the rest of the configuration is the same in the ESXi command line but still same issue

      guide: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1035833


      any idea how to fix this?


      thanks a lot

        • 1. Re: ESXi 5.5 NTP Client not getting sync
          jlanders Expert
          VMware Employees

          We're obviously not experts on the Windows time service, but an NTP query from ESXi to a Microsoft Domain Controller will not work (that is, ntpq -p will always fail) because the Windows time service does not support NTP mode 6 packets. These packets are control messages for NTP, To our knowledge, the Windows time service supports mode 3 (client) and mode 4 (server) packets, but not mode 6 packets.


          According to this Microsoft KB article: How to configure an authoritative time server in Windows Server "The PDC master must not be configured to synchronize with itself." [Click on the + that is just after the sad looking faceless person holding a wrench.]


          If you really want to synchronize your ESXi server with an Windows Active Directory Server that has no upstream servers, you must do three things via regedit on your Windows 2008 R2 server. First, in W32Time/Config, set AnnounceFlags to 5. Second, in W32time/Config, set LocalClockDispersion to 1. Third, in W32Time/Parameters, set Type to NoSync. Exit regedit, stop and start the w32time service.


          I can't say that I would recommend this approach, but it should work.

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