XCCC: "HTTP 404" Error Appears When You Try to Log On to OWA Through a Front-End Server in a Cluster

When you try to log on to Outlook Web Access through an Exchange 2000 front-end server in a "front-end and back-end" cluster topology, you may receive the following error message: However, you can successfully log on to Outlook Web Access if you bypass the front-end server by logging on to Outlook Web Access through an Exchange 2000 Server that serves as a back-end server in the cluster.

To let users to log on to Outlook Web Access through the front-end server, use either of the following methods.

Remove the host header NetBIOS name

If your default Web site is shut down, edit the existing virtual server entry, and then delete the entry in the Host Name box so that it is blank. To do this, follow these steps:

1. Start Exchange System Manager.
2. Expand Servers, click the appropriate server name, expand Protocols, and then click HTTP.
3. Right-click Exchange Virtual Server, and then click Properties.
4. Click Advanced (located to the right of the IP Address menu), and then click Edit.
5. Clear the Host Header Value, and then click OK three times.
6. Quit Exchange System Manager.

For example, in a scenario where the NetBIOS name of the Exchange virtual server is BACK_END_SERVER and the Exchange virtual IP address is 192.168.0.1, the original entry would look similar to the following:

In this example, the existing Host name BACK_END_SERVER would be cleared.

Add Host Headers on your back-end servers

1. Start Exchange System Manager.
2. Expand Servers, click the appropriate server name, expand Protocols, and then click HTTP.
3. Right-click Exchange Virtual Server, and then click Properties.
4. Click Advanced (located to the right of the IP Address menu), and then click Add.
   
   Do not remove the existing host header name, for example, the Exchange Server computer virtual net name. Exchange Server Cluster Services requires a specific virtual server name in the Host Header field.
5. Add the following host headers. (The IP address is still the same; only the host header name changes.)
   • The NetBIOS name of each front-end server.
   • The NetBIOS name of the cluster resource.
   • The IP address of each front-end server.
   • The fully qualified domain name (FQDN) of the front-end server or servers.
   • The IP address of the back-end server.
   • The NetBIOS name of the back-end server.
6. For fault tolerance, make the same changes on the second node of the cluster.
   
   If you are using Windows Load Balancing, you also have to add a host header for the virtual IP address of the Windows Load Balancing resource. Additionally, it may be useful to add host headers to your front-end servers.

Host headers permit you to host multiple virtual Web servers by using the same IP address and TCP port, instead of having to use a unique combination of IP address and TCP port for each virtual server.