Global Catalog servers use two primary ports for communication: TCP port 3268 for standard queries and TCP port 3269 for secure queries over SSL. These ports facilitate the retrieval of directory information from the Global Catalog in Active Directory environments. Additionally, the standard LDAP port (TCP 389) is also used for regular directory services communication, but for Global Catalog specifically, ports 3268 and 3269 are essential.
The ports used by GC is as follows GLOBAL CATALOG 3268 GLOBAL CATALOG 3269 https(secure)
Global catalog server
Global Catalog
The GLobal Catalogue has a reference to all objects within Active Directory. Its is know as GC
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SMTP
"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." http://technet.microsoft.com/en-us/library/cc728188(WS.10).aspx
Global catalog server.
Global Catalog
Universal groups add more data to the global catalog.
This checkbox makes the directory structure within a computer network forest transparent to users who perform a search on the network. This information is auto catalogued in the Global Catalog.
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