A logical datacenter diagram defines or documents specific configurations of application server software, such as Internet Information Server, SQL Server or BizTalk Server, that have a specific purpose such as a secure front-end Web server. The diagram shows how these configured logical (application) servers are interconnected.  Logical servers can be grouped within zones which define logical communication boundaries.  Zones can be configured to constrain the kinds of logical servers they can contain and the direction and kinds of communication that can flow into and out of the zone.