What Is a Domain Controller?

Domain controller means that in the "domain" mode, at least one server is responsible for the authentication of each computer and user connected to the network. It is equivalent to a unit's gatekeeper and is called a "domain controller" DC) ".

A domain controller (DC) is the storage location of Active Directory. The computer on which Active Directory is installed is called a domain controller. When Active Directory is installed for the first time, the computer on which Active Directory is installed becomes the domain controller, referred to as "domain controller." Domain controllers store directory data and manage user domain interactions, including user login processes, authentication, and directory searches. A domain can have multiple domain controllers. In order to obtain high availability and fault tolerance, smaller domains need only two domain controllers, one for practical use and the other for fault tolerance checking; larger domains can use multiple domain controllers. ^[1]

The domain controller contains a database of user accounts, passwords, and computers belonging to the domain. When a computer is connected to the network, the domain controller must first identify whether the computer belongs to the domain, whether the login account used by the user exists, and whether the password is correct. If the above information is incorrect, the domain controller refuses the user to log on from this computer. If you cannot log in, the user cannot access the resources that the server has permission to protect, and can only access Windows shared resources as a peer-to-peer user. This protects the network resources to a certain extent.

In fact, the domain and the working group are very similar in structure, but their expressions are slightly different:

1. Working group: Only a small number of computers can be connected into a network that can share resources with each other. In this working mode, the security of information can only be set by setting a password for the shared information or setting the use permissions to special users to realise.

2. Domain: The domain controller is used for information management. Each user has its own account and password, and can be given different usage rights according to different situations. This method not only ensures the security of network information is very good. , While also meeting the requirements of large and medium-sized networks. ^[2]

The domain controller Active Directory forest can be updated in two ways: upgrade or migration. You need to know what major changes have occurred to the domain controller before and after the domain controller update.

One of the benefits of domain controllers is that you can get Windows Server 2012 R2 domain and forest-level features. Domain controllers include the benefits of all previous levels of features.

The disadvantage of upgraded domain controller functions is that they may be limited to operating systems that only support domain controllers. For example, if you upgrade the domain controller functional level to Windows Server 2012, you can only use domain controllers running Windows Server 2012 and Windows Server 2012 R2 functional levels.

Increasing the functional level of a domain controller does not mean that all servers cannot run earlier versions of the operating system. For example, you can still run a Windows Server 2003 server on a Windows Server 2012 R2 functional level domain controller.