the following scenario.
- In a Microsoft Office Exchange Server 2007 environment,
Client Access server (CAS) servers
exist in multiple Active Directory Sites.
- Client-facing servers CAS A1 and CAS A2 are located in Active
Directory Site A. CAS servers CAS B1 and CAS B2 are located in Active
Directory Site B.
- A load balancer exists in front of the CAS servers in
Active Directory Site A. For example, the https://mail.contoso.com URL resolves
to a load balancer that proxies HTTPS connections to either
of the two CAS servers within Active Directory Site A.
- You have a mailbox that is located on an Exchange Server
server in Active Directory Site B.
- All CAS servers in Active Directory Site B are configured
as nonclient-facing CAS servers. These configurations are set to the NULL value for the ExternalURL
property in the OWA virtual directories.
- You try to access your mailbox by using Microsoft Office
Outlook Web Access through the https://CASA1.contoso.com/owa URL or
through the https://mail.contoso.com/owa URL.
Note The target mailbox and the client-facing CAS servers do not exist
in the same Active Directory Site. Therefore, a
client-facing CAS server proxies the HTTPS connection to an internal CAS server
in Active Directory Site B. In this scenario, the client-facing CAS A1 server
proxies the user’s connection to one of the internal CAS servers. Then, the
internal CAS server accesses the user’s mailbox in Active Directory Site
In this CAS-to-CAS proxy environment, you log on to Outlook
click the Options
click the About
item on the navigation bar to view
various information about CAS servers.
However, the Proxy server name
field on the Outlook
Web page incorrectly shows either
"CAS B1" or "CAS B2"
instead of the “CAS A1” client-facing server. In
this scenario, it is difficult to troubleshoot the data path
because the About
page does not provide the name of
the client-facing CAS server in the Proxy server name
time and interpret the
logs on all CAS servers in Active Directory Site A.
Then, you can
determine whether you
client-facing server CAS A1. Note
This problem may
without load balancers or if you have only one CAS server
for each Active Directory Site.
incorrect proxy server name is caused by a code defect
that occurs in the CAS-to-CAS proxy environment.
To resolve this problem, install the following update rollup:
Description of Update Rollup 2 for
Exchange 2007 Service Pack 2
a CAS-to-CAS proxy environment, the following fields exist on the “About" page:
- Outlook Web Access host address: Provides the URL of the
internal CAS server.
- Outlook Web Access Proxy Host Address: Provides the URL
that is entered into your
Web browser. Frequently, this is the name of the load-balanced
- Proxy server name: Provides the
fully qualified domain name of the client-facing CAS server.
- Client Access server
name: Provides the fully qualified domain name of the internal CAS
For more information about how a
can act as a proxy for other CAS
servers in an
organization, visit the following Microsoft Web site:
has confirmed that this is a problem in the Microsoft products that are listed
in the "Applies to" section.
Article ID: 977425 - Last Review: January 22, 2010 - Revision: 1.0
- Microsoft Exchange Server 2007 Service Pack 2, when used with:
- Microsoft Exchange Server 2007 Enterprise Edition
- Microsoft Exchange Server 2007 Standard Edition
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