What is important to document in an active directory server?

First, be careful not to document Active Directory itself. Microsoft has already done that. It is not your responsibility, and it will reduce the time you have to document the configurations, policies, and procedures specific to your installation.

Here is a list of things that you should document.

• Explain your computer, user, domain, and OU naming conventions.
• Describe your OU hierarchy and the reasoning behind it.
• Briefly describe the main functions of your Group Policy Objects and why you organized them as you did.
• Describe your network numbering conventions and DHCP configuration, if applicable.
• Describe your DNS configuration.
• Describe your Windows Firewall exceptions.
• List the the Windows Server roles and third-party software installed on each server.
• Note the locations of Active Directory's FSMO roles.
• Describe the organization's policy for when to add new user accounts or revoke existing user accounts.
• Describe the organization's policies for user restrictions (related to GPO details above).
• If you are responsible for the network as well, provide a building wiring diagram.

Might be OTT for a smaller church, but the Microsoft Active Directory Topology Diagrammer is pretty funky. It automatically generates a diagram of your Active Directory topology in Visio.

Diagrams can be made of servers, domains, sites, routing groups, admin groups and connectors. It shouldn't take long to produce some nice illustrations that you can use to supplement your written handover notes.

Screenshot here (on a Sun blog!)