FSMO Roles and GC Explanation

What are Operations Masters? - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/6a773f69-e153-4460-9a9b-014e98110bab.mspx

Because AD operates in a Multi-Master environment, FSMO roles are used for specific components and functions that must be centralized and managed. They also (like in the case of the PDC Emulator) often have functions designed for legacy compatibility with older operating systems like NT and Win9X. This article gives a good overview of these pieces, what their dependencies are, and what they mean to you as an admin.

How Operations Masters Work - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/795229a5-8a74-4edb-a2f4-d5794d31c2a7.mspx

A complete breakdown (per role) of how each of the 5 roles (RID, PDCE, Domain Naming, Schema, and Infrastructure) operate in practical terms, and how they should be managed.

What Is the Global Catalog? - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/24311c41-d2a1-4e72-a54f-150483fa885a.mspx

An excellent explanation of GC's and what they do in a domain environment. Many systems (like Exchange) rely on this special virtual partition, and certain functional modes (starting with 2000 Native Domain) raise the need for this as well.

How the Global Catalog Works - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/440e44ab-ea05-4bd8-a68c-12cf8fb1af50.mspx

A lengthy treastise on the 'under the covers' workings of GC's, what the default settings are, how it's populated and updated, and other elements important to troubleshooting issues.

Global Catalog Tools and Settings - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/0d34c3b9-499b-41d3-a55f-527ce61e7858.mspx

Finally, the tools that can be used to monitor and manipulate GC's (DSSITE, LDP, ADSIEDIT, and REPADMIN), plus the various registry values important to the GC system, especially for Universal Group caching in 2003.