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    Best Practice for Time Sync for Active Directory Domain Controllers

    IT Discussion
    windows active directory ntp sntp
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    • S
      scottalanmiller
      last edited by

      I'm going to turn this into its own topic.

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      • D
        Dashrender @scottalanmiller
        last edited by

        @scottalanmiller said:

        I'm going to turn this into its own topic.

        OK
        🙂

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        • D
          Dashrender
          last edited by

          I looked at the settings in ESXi, it was not set to pull time from an external source. I have corrected that, and enabled NTP.

          ESXi is now correct on it's time, now to force the PDC emulator to sync.. and eventually all windows clients will sync as well.

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          • D
            Dashrender
            last edited by

            OK tried a

             w32tm /resync
            

            and got back

             The computer did not resync because no time data was available.
            
            C S 2 Replies Last reply Reply Quote 0
            • C
              coliver @Dashrender
              last edited by

              @Dashrender said:

              OK tried a

               w32tm /resync
              

              and got back

               The computer did not resync because no time data was available.
              

              If I remember correctly it actually uses VMWare tools to do the syncing between the computers and the hypervisor.

              S 1 Reply Last reply Reply Quote 1
              • S
                scottalanmiller @coliver
                last edited by

                @coliver said:

                @Dashrender said:

                OK tried a

                 w32tm /resync
                

                and got back

                 The computer did not resync because no time data was available.
                

                If I remember correctly it actually uses VMWare tools to do the syncing between the computers and the hypervisor.

                It you are on VMware ESXi, then the VMware tools are the only possible mechanism for that.

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                • D
                  Dashrender
                  last edited by

                  OK, I have VM Tools running - do I just wait and see?

                  S 1 Reply Last reply Reply Quote 0
                  • S
                    scottalanmiller @Dashrender
                    last edited by

                    @Dashrender said:

                    OK tried a

                     w32tm /resync
                    

                    and got back

                     The computer did not resync because no time data was available.
                    

                    What time source do you have set? w32tm requires an SNTP source to sync to, what SNTP server do you have it talking to?

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                    • D
                      Dashrender @scottalanmiller
                      last edited by

                      @scottalanmiller said:

                      @Dashrender said:

                      OK tried a

                       w32tm /resync
                      

                      and got back

                       The computer did not resync because no time data was available.
                      

                      What time source do you have set? w32tm requires an SNTP source to sync to, what SNTP server do you have it talking to?

                      I don't, it's currently pulling from

                       Local CMOS Clock
                      
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                      • S
                        scottalanmiller @Dashrender
                        last edited by

                        @Dashrender said:

                        OK, I have VM Tools running - do I just wait and see?

                        There is no sync involved. You are mixing the concepts of NTP/SNTP with a source server and actually controlling the system's clock.

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                        • S
                          scottalanmiller @Dashrender
                          last edited by

                          @Dashrender said:

                          @scottalanmiller said:

                          @Dashrender said:

                          OK tried a

                           w32tm /resync
                          

                          and got back

                           The computer did not resync because no time data was available.
                          

                          What time source do you have set? w32tm requires an SNTP source to sync to, what SNTP server do you have it talking to?

                          I don't, it's currently pulling from

                           Local CMOS Clock
                          

                          Right, which is unrelated to time syncing.

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                          • D
                            Dashrender
                            last edited by

                            I'm lost
                            I said I did this.

                            @Dashrender said:

                            My current PDC emulator is set to pull time from the BIOS clock

                             C:\Windows\system32>w32tm /query /source
                             Local CMOS Clock
                            

                            This hasn't been an issue for years, yet someone called this morning and reported that the phones and the computers didn't match timewise, so I'm looking into it.

                            So my PDC emulator is pulling time from CMOS. If CMOS changes, won't the OS change too?

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                            • D
                              Dashrender
                              last edited by

                              Shouldn't this be in IT discussions? It's technical in nature.

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                              • D
                                Dashrender
                                last edited by

                                I guess my desire here was to have the ESXi host be the main source for time inside my network. It of course would pull time from the internet.

                                It sounds like this isn't going to work. So instead I have to have my PDC emulator pull it's own time from the internet, and the VM Hosts will have to be managed separately.

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                                • D
                                  Dashrender
                                  last edited by

                                  Here's the command to set your PDC emulator to sync with a time source

                                    w32tm /config /manualpeerlist: peers /syncfromflags:manual /reliable:yes /update 
                                  

                                  Replace peers with your FQDN or IP of the desired time servers.

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                                  • S
                                    scottalanmiller @Dashrender
                                    last edited by

                                    @Dashrender said:

                                    Shouldn't this be in IT discussions? It's technical in nature.

                                    Hmmm... I didn't choose the category, it just did it.

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                                    • S
                                      scottalanmiller @Dashrender
                                      last edited by

                                      @Dashrender said:

                                      I guess my desire here was to have the ESXi host be the main source for time inside my network. It of course would pull time from the internet.

                                      It sounds like this isn't going to work. So instead I have to have my PDC emulator pull it's own time from the internet, and the VM Hosts will have to be managed separately.

                                      ESXi can pull time from the Internet. If it is correct and the DC is getting its time from the ESXi clock then the ESXi is setting the DC which, in turn, uses SNTP to talk to the rest of the network.

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                                      • S
                                        scottalanmiller
                                        last edited by

                                        Here is vmware's older paper on how they recommend that this be set up:

                                        http://www.vmware.com/files/pdf/Virtualizing_Windows_Active_Directory.pdf

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                                        • S
                                          scottalanmiller
                                          last edited by

                                          Here is a more recent one:

                                          http://www.vmware.com/files/pdf/solutions/Virtualizing-Active-Directory-Domain-Services-on-VMware-vSphere.pdf

                                          1 Reply Last reply Reply Quote 1
                                          • S
                                            scottalanmiller
                                            last edited by

                                            VMware definitely recommends that you use an external time source to control drift, not using the ESXi virtualized clock.

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