How to configure Exchange 2016 to use 2 domain controllers?

Question

Hi, How can Exchange be configured so that when I reboot either of any 2 DCs for maintenance that Exchange continues to function normally? Now when I do a reboot of one of the DCs the Exchange seems to disconnect from the network and users get prompted to enter a password in their Outlook.

My goal is to be able to do system maintenance on either DC (one at a time of course) and not have Exchange bark about it.

Thanks.

Answer 1

To ensure that Exchange continues to function normally when rebooting one of the domain controllers (DCs) for maintenance, you need to configure your Exchange environment for high availability. This involves implementing redundant DCs and properly configuring the Exchange Server to utilize multiple DCs. Here are the steps you can follow:

Implement redundant domain controllers: Ensure that you have at least two domain controllers in your environment to provide redundancy. This way, if one DC is rebooted or temporarily unavailable, the other DC can still handle authentication requests.

Configure DNS settings: Verify that the DNS settings on the Exchange Server are correctly configured to include the IP addresses of both domain controllers. This ensures that Exchange can locate an available DC for authentication even if one is rebooted.

Configure Global Catalog servers: Ensure that both domain controllers are configured as Global Catalog (GC) servers. The GC contains a partial replica of all objects in the forest and helps Exchange to quickly locate the required user and configuration information.

Verify Exchange Server configuration: Check the Exchange Server configuration to ensure it is using both domain controllers. Open the Exchange Management Console (EMC) or Exchange Admin Center (EAC) and navigate to the Server Configuration. Review the properties of the Exchange server and ensure that the domain controllers specified include the IP addresses of both DCs.

Test failover: Perform a test by rebooting one of the domain controllers and verifying if Exchange continues to function normally. During the reboot, users should not experience any issues with Outlook or be prompted for passwords.

By implementing redundant domain controllers, configuring DNS and GC settings properly, and verifying the Exchange Server configuration, you can ensure that Exchange remains functional even when one of the DCs is rebooted for maintenance.

Answer 2

There is no way to check that from EAC. The IP addresses listed refer to the DNS settings, not the DCs

If a DC goes down, Exchange should be ok unless the other server is not compatible or cant be reached for whatever reason. However, having said that, I have seen issues with clients when there is only a few DCs available or the Outlook client is not cached mode.

What you can check is event 2080 on each server.

https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/msexchangedsaccess-event-id-2080

Make sure both DCs are reachable and usable by Excange.

If they are, then verify you havent hard coded the Exch Servers to any DC

You can run this for each server and verify it shows both:

Get-ExchangeServer -Identity “ServerName” -status | Select CurrentDomainControllers

It should show both.