Global Catalog(全局编目) review

参考：http://technet.microsoft.com/en-us/library/cc728188.aspx

The global catalog is a distributed data repository that contains a searchable, partial representation of every object in every domain in a multidomain Active Directory forest. The global catalog is stored on domain controllers that have been designated as global catalog servers and is distributed through multimaster replication. Searches that are directed to the global catalog are faster because they do not involve referrals to different domain controllers.

森林中可包括多个GC，分布式的存储Windows域森林中的域信息，每个域中可以有多个

信息一般是只读的，不完全的，如何存储是可配置的

用于提高访问森林中其他域主机的访问速度，无需referral to other domain controllers

而每个域控制器只存储本域的信息，但是可写的