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1. Start with OWA basics
If one of your OWA servers malfunctions, the first thing you should do is check the server clock. If the clock falls out of sync with your domain controllers, Kerberos authentication will fail. This leads to OWA and ActiveSync problems.
After you’ve checked the server’s clock, verify that the domain name system (DNS) name resolution works properly. I’ve traced many OWA problems to incorrect entries on internal DNS servers.
2. Client access server: To rebuild or not to rebuild?
Almost all the important Exchange configuration information is stored in Active Directory, not on Exchange servers. This makes things easier when you need to rebuild a malfunctioning Exchange server. In fact, you can completely rebuild your client access server (CAS) in about an hour using these simple steps:
- Make note of which version and service pack level your server operating system currently runs.
- Make note of which version and service pack level Exchange Server currently runs.
- Make note of your server name.
- Reset -- but do not delete -- the server’s Computer account in Active Directory.
- Format the server hard drive and install a clean copy of Windows. Be sure to use the same version and service pack level you used before. .
- Change the server name to match the one you used previously.
- Join the server to the domain with the existing computer account.
- Verify that your Exchange Server installation media is the same version and service pack level that you previously used.
- Install any Exchange Server prerequisite components.
- Insert the Exchange installation media and run the following command: Setup /M:RecoverServer.
This method almost always fixes an OWA problem, but it comes with a caveat. Remember that the CAS hosts services other than OWA. If you use these steps to repair the CAS, then OWA, Outlook Anywhere and ActiveSync will be unavailable for the duration of the repair unless you have other client access servers to handle the workload.
Even if you can do without these services for an hour or two, remember that if you’re on Exchange Server 2010, all your Outlook clients connect to the CAS. If you only have one CAS and take it down for repairs, none of your users can connect to Exchange.
You should also try to avoid using the technique described above if your CAS hosts additional Exchange Server roles or if you’ve made customizations to OWA.
3. Recreate your OWA virtual directory
OWA problems are often traced to virtual directories. You can usually fix a virtual directory problem without taking the CAS completely offline, but caution is in order.
The technique below explains how to recreate your OWA virtual directory. However, when you do, the virtual directory’s contents return to their default values. If you’ve made any OWA customizations, they will be erased and you will need to reload any custom OWA code after the operation completes.
Additionally, you must work with the OWA virtual directories through Exchange rather than through Internet Information Services (IIS). While it is possible to rebuild the OWA virtual directory at the IIS level, doing so is almost always problematic.
The easiest way to rebuild the OWA virtual directory is from the Exchange Management Console (EMC). The first step is to delete the old OWA virtual directory. Use the following command:
Remove–OwaVirtualDirectory –Identity ‘<server name>\owa (Default Web Site)’
For example, if you want to delete the OWA virtual directory from a server named Exch1, use the following command (Figure 1):
Remove–OwaVirtualDirectory –Identity ‘Exch1\owa (Default Web Site)’
Figure 1. Delete the OWA virtual directory through the Exchange Management Console.
After you’ve removed the OWA virtual directory, create a new one with the following command:
New-OwaVirtualDirectory –InternalUrl ‘https://<fqdn>/owa’ –WebSiteName ‘Default Web Site’
For example, to create a new OWA virtual directory on a server named Exch1 in the Contoso.com domain, use the following command (Figure 2):
New-OwaVirtualDirectory –InternalUrl ‘https://Exch1.contoso.com/owa’ –WebSiteName ‘Default Web Site’
Figure 2. Recreate the OWA virtual directory through the Exchange Management Console.
After creating the new OWA virtual directory, you must reset IIS. This will result in a brief CAS server outage, but the outage should only last a few seconds.
To reset IIS, use the IISRESET /NoForce command. Also, you must issue this command from an elevated command prompt window as opposed to a PowerShell window. You can see what this process looks like in Figure 3.
Figure 3. You must reset IIS through a command prompt window.
As you can see, there are several techniques for repairing OWA. The trick is in determining which approach is best for your OWA environment and your end users.
ABOUT THE AUTHOR:
Brien Posey is an eight-time Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and healthcare facilities. He has also served as a network administrator for some of the nation’s largest insurance companies and for the Department of Defense at Fort Knox.
This was first published in January 2012