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
SMTP
See related links.
Global catalog server.
"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
Universal groups add more data to the global catalog.
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.
I know the ans but i am not going to tell you guyz.