ADUC Extremely Slow Until ARP Cache Cleared

Question

Hello,

We are running Active Directory based on Windows Server 2016 and Windows 10 Education workstations.

People who have the Active Directory Users & Computers tool loaded on their computers are finding it very slow to load and operate. Like a minute or two after clicking the icon before anything appears. And then moving from one object to another takes forever once in.

In troubleshooting, I found that if you manually clear the ARP cache of the computer, then everything speeds up to normal. Clicking on it brings up the tool almost immediately. That only lasts temporarily, though. For example, reboot the computer and it's back to being slow until you clear the ARP cache again. I have no idea what connection the ARP cache could have to AD Users & Computers. I am stumped.

I do know that anything AD-related depends heavily on DNS, but I have verified that DNS settings are correct and flushing the DNS cache does not improve things like flushing the ARP cache does.

Any suggestions would be most appreciated.

Thanks,
Tom

Answer 1

Hello TomP,

I would recommend to:

• run a DCDIAG /v /c /q to ensure the connectivity of the DCs to ensure the health.
• Check the NIC DNS Binding
• Ensure DCs have a round robin DNS setting (Ensuring a Mesh structure of DNS configuration in the DCs)
• Perform a flush of DNS:
  ipconfig /flushdns
  ipconfig /registerdns
• In case you detect a unhealthy DC, you can always perform a metadata cleaunp for that DC specifically:

https://learn.microsoft.com/en-US/windows-server/identity/ad-ds/deploy/ad-ds-metadata-cleanup

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