Recovering Exchange Server DAG Member Node

Overview

If a Mailbox server that’s a member of a database availability group (DAG) is lost or fails, and is unrecoverable and needs replacement, you can run a server recovery operation.

Deployment of Underlying Physical/Virtual Machine & Base Windows Server OS

Provisioning of Physical/Virtual Machine (Virtual Disks in Thick Mode)
Installation & Configuration of Windows Server
Configuration of Partitions & Assigning Drive Letters (same as primary server)
Installation & Configuration of Prerequisites required for Exchange Server (according to the installed edition)

What you need to verify before begin

If Exchange is installed in a location other than the default location, you must use the /TargetDir Setup switch to specify the location of the Exchange program files. If you don’t use the /TargetDir switch, the Exchange program files will be installed in the default location (%programfiles%\Microsoft\Exchange Server\V15).

To determine the install location, follow these steps:

Open ADSIEDIT.MSC or LDP.EXE.
Navigate to the following location: CN=ExServerName,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=ExOrg Name,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=DomainName,CN=Com
Right-click the Exchange server object, and then click Properties.
Locate the msExchInstallPath attribute. This attribute stores the current installation path.
Reset Computer Account (lost DAG server node) in Active Directory
Remove old passive DB copies
Remove lost DAG Node from DAG Interface in Exchange Admin Center