Global Catalog Server 2003/2008

GC consists of an index stored on Active directory Servers. It
containts the name of all the objects on the AD server. The gc also
contains a handful of searchable attributes for example. dn names,
first name, last name and lot more these things can be controlled and
viewed by diff tools like ADSIEDIT and LDP. for more information
please got through the articles listed below. KB 248717 kb 232517


Thanks

[WajeehT]

you can activate the Schema MMC snap-in by going through the following steps:

• Go to: Start > Run > mmc and click on OK button.
• MMC Console menu will appear
• Now, click on the Add/Remove Snap-in option
• Click on Add > Active Directory Schema > Add
• Finally click on Close button, followed by clicking on OK button.