Customizing the global catalog

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Customizing the global catalog

There may be instances where you will need to customize the global catalog to include additional attributes. However, you will want to carefully consider your options as changes to attributes can impact network traffic. By default, the global catalog contains an object’s most common attributes for every object in the entire forest, which applications and users can query. For example, you can find a user by first name, last name, e-mail address, or other common properties of a user account.

To add additional searchable attributes to the global catalog, administrators can use the Active Directory Schema snap-in. For more information about adding additional attributes to the global catalog, see Add an attribute to the global catalog.

When determining whether or not to add an attribute to the global catalog, consider only adding additional attributes that are frequently queried and referenced by users or applications across the enterprise. Also consider how frequently an attribute gets updated during replication. Attributes that are stored in the global catalog are replicated to every global catalog in the forest. The smaller the attribute, the lower the impact of that replication. If the attribute is large, but very seldom changes, it will have a smaller replication impact than a small attribute that changes often.

For more information about attribute definitions, see the Active Directory Programmer's Guide at the Microsoft Web site.

Important

• It is strongly recommended that you use global groups or universal groups instead of domain local groups when specifying permissions on domain directory partition objects replicated to the global catalog. For more information, see Global catalog replication.

Notes

• In Windows 2000, adding a new attribute to the global catalog causes a full synchronization of all of the domain data from all of the domains in the forest. In a large, multi-domain Windows 2000 forest, this synchronization can cause significant network traffic. Between domain controllers enabled as global catalogs that are running Windows Server 2003, only the newly added attribute is replicated.

• When deciding whether or not to include an attribute in the global catalog, remember that you are trading increased replication and increased disk storage on global catalogs for potentially faster query performance.