Mar 2009 ... Active Directory (AD) is a technology created by Microsoft that provides a variety of network services, including: ...
en.wikipedia.org/wiki/Active_Directory - 112k - Cached - Similar pages
Very basically it's a system for administrators of a network to centrally manage computers, users, other network resources and security from a central location (the domain controller)
For example, if a new user was starting in a company with AD then all the administrator would have to do is setup the user on the domain controller and then that user could then log into any computer on the network (without actually having to setup a user account for them on each computer) and all the correct access and security rights would already be assigned to them
it goes far beyond that basic example and is in fact a very powerful tool, but as said if you want more details then google it, there is lots about it
but yes, to have AD you need at least one domain controller (which will be a primary domain controller, or PDC) which will require you to have windows server (onwards from 2000) also there are several different versions of each of them (server 2000, 2003, 2008) and some versions of each can not act as a PDC
It's possible to setup a free linux based PDC, but as you have to ask what it is that is then sorry, but that's not a route I'd suggest!
We use Active Directory in a domain with about 120 computers. A simple intuitive interface allows virtually everything about every computer to be controlled and modified in an automated way.
Rules can be set on a per machine and a per user basis. Each PC is in contact with a server and takes instructions about a wide range of settings. These policies are maintained by the servers under the supervision of a Domain Controller.
A central function is security. Users are authenticated across the network. A roaming profile maintained by the servers allows a user to be recognised with their data files and desktop consistent across all workstations.
Printers can be automatically installed by the servers when the PC boots. Drive mappings and file access right can be assigned for user groups and easily changed.
All the information is shared among the servers on a configurable schedule ensuring a fault tolerant network. Domain controllers work together so usually several servers are given this status.
The servers maintain the Microsoft upgrade path with one server downloading from Microsoft and distributing the updates first to other servers and then on to the PC.
Programs can be upgraded, installed and configured by scripts. A simple interface is provided for Microsoft Office products allowing administrators to control the user interface of machines across the network. For example the default save format for Office components can be set to the 2003 version to maintain compatibility across a network of mixed version Office installations.
Windows and Linux understand each others needs and there are many tools available to hepl them work together.
Linux is great for utility work like mail servers and proxies but the Windows networking services on a well organised domain are in a class of their own.
KOSTER you can't always get reliable answers from some people but luckily the people that have replied are genuine as I have had replies many a time from Chuckfickens,so don't be so hasty in slamming me down when I tried to help. I have often put a sensible question up and got some bright spark coming back with silly replies.and that does not go for me only.