What Is the Global Catalog?

In a separate domain, AD DS database it contains all the information about each object in this area. This information is not Copy Outland. For example, a Query AD DS object is directed to a Domain controller for that domain. Whether there are multiple domains in the forest, then the query does not provide any results Things in different areas. Enable Looking across multiple domains, you can Configure one or more domain controllers A copy of the global catalog store. 

Global catalog is a distributed database each domain contains all the objects in a multi- domain forest can search for representation. By default, the only global catalog servers in the first forest root domain controller created area

 Global directory does not contain all the properties of each object. On the contrary, the general maintenance directory most likely in search of useful cross-domain attributes subset. The property Including name, display name and location. There are a variety of reasons, you can the search for a global catalog, rather than that is not a global catalog domain controller. For example, When the Exchange server receives incoming e-mail, it needs to search for the account to the recipient It can determine how to route the message. By automatically query the global catalog, Exchange Server The recipient will be able to find in a multi- domain environment. When users log on to their Active Directory accounts, perform domain controller must be a global certification Check the universal group membership before the user directory for authentication.