A. Actually, I know of two. One is the Microsoft Exchange Server Topology Diagramming Tool (exmap.exe), which you can download from http://www.microsoft.com/exchange/downloads/exmap.htm. This tool uses ADO to read an Exchange Server organization’s directory and turns the directory into a Visio 5.0 diagram showing sites, servers, and connectors. That’s all it does, but it’s free (you must have Visio 5.0 or later to run it) and it includes source code, so you can customize it to meet your needs.
The other tool is Ecora Documentor for Microsoft Exchange. This very nice commercial tool generates automatic documentation of your Exchange Server architecture and topology and is a terrific way to get an overview of that group of servers you just inherited. The report contains a significant amount of detail that can be useful if you’re trying to understand, preserve, or replicate your servers’ configuration.