This behavior occurs because of changes that are introduced in Microsoft Exchange Server 2003. In previous versions of Microsoft Exchange, when you create a new virtual server instance, the host name of the cluster node was bound as the host header name. However, in Exchange Server 2003, the default binding of an Exchange virtual server does not contain a host header name.
This behavior permits you to more easily configure additional host headers, such as fully qualified domain names (FQDNs) and front-end server names in larger organizations.
The following behaviors occur when you install Exchange Server 2003:
- An Upgrade Installation:
When you upgrade to Exchange Server 2003, the existing configuration is not changed. If the HTTP virtual servers have bindings with the host name, they are not removed. This behavior makes sure that the upgrade process does not introduce unwanted behaviors in a configuration that previously worked. - A Non-Cluster Installation
When you perform a new Exchange Server 2003 installation, and create a new HTTP virtual server, the default binding does not include the server host name bound as the host header name. The host header is blank. - Installation on a Cluster Node
When you install Exchange Server 2003 on a cluster node, Setup creates the default HTTP virtual server instance with a blank host header.