Five Steps to Rebuild Exchange client access server

Most of the documentation  backing up Exchange Server 2007 and Exchange 2010 states that it isn’t necessary to back up your client access server (CAS). This makes sense because all of a client access server’s configuration information is stored in Active Directory. That said, you should still know how to rebuild a failed server.

If your CAS fails due to an irreparable hardware problem; follow these steps to repair it:

Reset the client access server’s computer account within the Active Directory Users and Computers console. Do not delete the account.

Install Windows on the new server and then install the same OS version as the failed server.

Rename the server to match the name the CAS used and join the server to your domain.

Depending on the version of Exchange Server and service pack you were running, insert the corresponding installation media into the server and run the following command:

Setup.com /M:RecoverServer

After the command runs, Setup will install the Exchange binaries and use the information stored in Active Directory to rebuild your CAS.

Note: This technique can also be used to rebuild any other Exchange Server roles, except for the edge transport server.

These steps work well to rebuild a failed client access server; however, there is a major caveat. This method only works if the server is running a standard configuration, which is unlikely since many organizations personalize their Outlook Web Access interface.

Using these steps will rebuild the CAS to a functional state, but any OWA customizations will be lost. This happens because Setup copies the Exchange binaries from the installation media, not your customized files.

Rebuilding a CAS and recovering OWA customizations
You have two options for recovering OWA customizations after rebuilding your client access server:

Perform a full server backup, then restore the entire server.

Make a backup of your customizations, then rebuild your CAS using the five step outline above. After that, you can restore your OWA customizations from backup.

In my environment, I only back up OWA customizations. In the event of a failure, my infrastructure is configured such that Exchange Setup rebuilds the CAS and then I manually restore customizations.

Although configuration information stored in Active Directory may change slightly, binaries on the server itself probably won’t change unless you install a patch or perform additional customizations.

Considering the static nature of a CAS, it’s tempting to make a full server backup and then store your backup in a fireproof vault. The only problem is that a full backup will quickly become outdated.

Windows periodically resets the password associated with Active Directory accounts, which gives your backup a limited shelf life. Depending on the version of Windows your CAS is running, the backup may only be relevant for 60 days. This happens because the password breaks synchronization with the password stored in the backup.

You can also reset the computer account password to use your backup, but it’s easier to back up only customizations. That way, you don’t have to worry about your backup becoming outdated — as long as you make a new backup with each additional customization.