Many IT learners have asked me to simplify the basis definitions, I am trying to put it in my own words making it simple to understand.
What is a forest?
The term "forest" can be described as collection of AD domains that share a single schema.
All DC's in the forest share this schema and it is replicated in a hierarchical fashion among them.
What is Schema?
Schema is nothing but the templates used to create an object in AD. The schema will have the template present even if the object is not present.
Example : I do not have a printer in the network, still the schema will have the template readyfor the printer .
What is Active Directory?
"Active Directory is the directory service used in Windows Server 2000,2003 & 2008 and is the foundation of Windows distributed networks. It can be described as collection (database) of network objects and resources. Objects can be users, printers, computers, OUs...etc
The core of Active Directory is a combination of an LDAP server and MIT Kerberos 5 KDC running on a Windows 2000,2003,2008 server acting as a domain controller that work as a unit to provide authentication ("Who are you?") and authorization ("What are you allowed to do?") information within a group of interlinked systems.
What is a Domain?
In Windows 2000, 2003 and 2008 a domain defines both an administrative boundary and a security boundary for a collection of objects that are relevant to a specific group of users on a network.A domain is an administrative boundary because administrative privileges do not extend to other domains.It is a security boundary because each domain has a security policy that extends to all security accounts within the domain. Active Directory stores information about objects in one or more domains.
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