Today we are announcing the availability of quarterly Cumulative Updates (CUs) for Exchange Server 2016 and Exchange Server 2019. These CUs include fixes for customer reported issues, all previously ...
Updated Jun 29, 2021
Version 1.0
Blog Post
Just in case anyone else has this issue, I pulled out the next few entries from my setup logs and sanitized them a bit. It looks like PrepareAD iterates through all defined domain controllers from your logs and mine. Then CN's below are for Microsoft Exchange System Objects, msExchSystemObjectContainer; Exchange Install Domain Servers, Global Security Group, and Exchange Servers, Universal Security Group?
[07/19/2021 16:15:20.0428] [2] Used domain controller DC01.domain.local to read object CN=Microsoft Exchange System Objects,DC=domain,DC=local.
[07/19/2021 16:15:20.0554] [2] Used domain controller DC01.domain.local to read object CN=Exchange Install Domain Servers,CN=Microsoft Exchange System Objects,DC=domain,DC=local.
[07/19/2021 16:15:35.0568] [2] Used domain controller DC01.domain.local to read object CN=Exchange Servers,OU=Microsoft Exchange Security Groups,DC=domain,DC=local.
Again, not sure if any of that will help you or anyone else.