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zvonko1214-2627 avatar image
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zvonko1214-2627 asked DSPatrick commented

Active Directory losing network

Hi,
experiencing a problem last days when our Domain Controller becomes inaccessible by Domain Computers.
It happens once a week and when we restart an external Cisco switch that is conneced to the server, everything becomes normal.
The same switch is used by other computers and they normally work but DC server, which is a VM hosted
on a Hyper-V Core Server, stops working with no reason. The Hyper-V Core Server host is also accessible without problem,
connected to the same switch.
So, we think that the switch is not a problem, it could be something on the DC virtual machine that is cleaned up by restarting the switch,
i.e by resetting the host or VM network adapters. In Event Log on the DC virtual machine and in the Event Log of the Core Hyper-V server
we can not find anything related to the problem. Both, DC and Hyper-V Core server are running windows 2016 Server OS.

Please can you advice me about what could cause behavior like this?

Regards.

windows-active-directory
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DSPatrick avatar image
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DSPatrick answered DSPatrick edited

Remove the 192.168.100.250 address from the domain controller's connection properties, then do ipconfig /flushdns, ipconfig /registerdns, restart the netlogon service. Domain controller and all domain members must use the static ip address of DC for DNS and no others such as router or public DNS

If problems persist then put up a new set of files to look at (including ipconfig /all > C:\problemworkstation.txt)

--please don't forget to upvote and Accept as answer if the reply is helpful--










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DSPatrick avatar image
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DSPatrick answered

Please run;

Dcdiag /v /c /d /e /s:%computername% >C:\dcdiag.log
repadmin /showrepl >C:\repl.txt
ipconfig /all > C:\dc1.txt
ipconfig /all > C:\dc2.txt
ipconfig /all > C:\problemworkstation.txt

then put unzipped text files up on OneDrive and share a link.



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zvonko1214-2627 avatar image
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zvonko1214-2627 answered

Hi Dave,
thank you for the answer, I uploaded the logs to Onedrive, here is the link:

https://1drv.ms/u/s!AphlujMliJTba4DOst-vqz3NeM8?e=4SXGcE

I put dc log only for one dc since we have only one dc in our network.

I did not upload problemworkstation log because when problem happens all workstations have problem with communication to DC.
All workstations are in the same network as DC (192.168.100.x). If you still need it, please tell me and I will ask one of users to send me the log.

Regards.

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zvonko1214-2627 answered

Hi Dave,
on more detail, the IP address of primary DNS (the DC itself) I added yesterday because it was missing, i.e the primary DNS was configured
with IP address of external DNS which is now secondary. So, this configuration is set after we restarted the switch and we can see, if the problem happens again then it means it did not help.

Regards.

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zvonko1214-2627 answered DSPatrick commented

Hi Dave,
thank you very much,
yes, it's possible that this config that is done in the past causes these problems.
I will let you know what is outcome of the new setting, We have to wait at least one week to see :-)

Regards.

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Ok, sounds good, also check your DHCP server (if there is one) is handing out only the domain controller address for DNS


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