Domain Controller

What is a domain controller?

A domain controller is a server responsible for managing and authorizing identity and network security requests. The main purpose of a domain controller is to accept authentication requests from machines and accounts in the same domain. If there is more than one domain controller within the same domain, any change must be allowed first. Whether a domain controller will allow a change heavily depends on the admin chosen configuration. If a change is allowed and performed, all domain controllers receive the same information with the help of the serves that replicate the performed change.

What is the difference between Active Directory and Domain Controller?

Domain Controller is a server on an Active Directory that is responsible for managing and authenticating requests from users and devices. An Active Directory, on the other hand, is a set of services that enables the connection between the user and the network. Another way to illustrate the difference between the two would be to present Active Directory as a directory service while a Domain Controller serves the service on the domain network. An Active Directory usually stores objects such as users and computers in a centralised database. Domain Controllers authenticate users and computers to join the specific domain.

What are the main functions of a domain controller?

The primary function of a domain controller is to validate and authenticate users and devices on the network. When a user requests to log into their domain, a Domain Controller checks their credentials such as password, username and others. Based on these, the Domain Controller either grants access to the user or denies it. According to the admin’s configuration, all Domain Controllers within the same domain need to allow a change before it is implemented. Appointing multiple Domain Controllers within the same domain increases the fault tolerance in case one of them goes unexpectedly offline.

Why is a domain controller important?

A Domain Controller manages the access to the domain by either allowing or blocking unauthorized access. This segmentation is based on the credentials, computer names, and group policies that the Domain Controller manages. Since this information is usually needed by hackers to break in the network, Domain Controllers are usually the focus of cyberattacks. This increases the importance of a Domain Controller and its adequate maintenance.

Who needs a Domain Controller?

Businesses from any area and size can make use of Domain Controllers as long as a unified system of rules and data proves to be useful. The data managed by a Domain Controller usually includes users, credentials, groups, rules of permission to access the network, and group policies. If a company is storing customer data on its network, in practice it would need a Domain Controller to increase its network security. While many organisations opt for hybrid environments, most of those still maintain a local Active Directory environment due to data sensitivity.

How are domain controllers set up in Active Directory?

The first step in the setting up of an Active Directory is to install Active Directory Domain Services (ADDS). For this, an user with administrative rights needs to log in to the Active Directory Server and open the Server Manager and choose Add roles and features from the Roles Summary. If the Domain Controller will be deployed in a virtual machine, the installation type should be Remote Desktop Services installation. Otherwise, the Role-based or feature-based installation should be selected. Under Server Selection, the destination server appointed as a Domain Controller must be chosen. To ensure this, the IP address must be correct. To appoint the server as a Domain Controller, the admin must choose Active Directory Domain Services from the menu item Server Roles on the left. The default features for the Domain Controller would be chosen automatically and can be found under Features. The last step of setting up an Active Directory Domain Services is to select Restart the destination server automatically if required box under the menu item Confirmation.

The second part of the Domain Controller configuration is to promote the selected sever into a Domain Controller. This is done through the Active Directory Domain Services Configuration Wizard. The first menu item Deployment Configuration on the left allows the admin to Add a new forest and enter a root domain name. Note that the root domain name is also the forest name. When selecting forest- and domain functional level, the latter must be equal to or higher than the formal. When setting up a first Domain Controller, it becomes the DNS server by default. In order to retrieve any Active Directory data, the admin must enter a unique password for the Active Directory Restore Mode. Under the menu item Additional Options, the user can add a NetBIOS domain name. Microsoft has appointed a few restrictions regarding the NetBIOS names such as disallowed characters (?, *, :, /, \, “), name length (1-15 characters) and reserved names (WORLD, USERS, DOMAIN). The menu item Paths allows users who set up the Domain Controller to choose where the database, log files and SYSVOL will be saved. It is usually recommended to respect the default settings. The last step of setting up a Domain Controller is to review the Prerequisites Check and proceed with the installation.

What are the benefits of domain controller?

Domain Controllers manage important credentials and group policies which enable the centralized user and device management across the Active Directory domain. This centralized control over user accounts is among the most important benefits of using a Domain Controller, as it allows companies to easily add and remove employees and manage their log-in credentials including passwords and usernames. Additionally, Group Policy objects allow admins to create password policies and to enforce multiple rules over software installation and the overall security. Setting up password policies directly contributes to lowering the risk of data breaches, as one of their main cause is inadequate passwords. The centralization that Domain Controllers offer also facilitates the recourse sharing across the domain. For example, if a company acquires a new printer, computer or other devices, they do not need to be set up separately on each domain user.

What are the limitations of domain controllers?

Setting up a Domain Controller includes and requires well-rounded planning and technical knowledge. Due to its centralization and authorization services, Domain Controllers could be targets in the event of cyber-attacks. Poorly maintained and unsecured Domain Controllers usually are more vulnerable and thus more likely to get hacked. Companies can prevent this from happening by implementing regular monitoring and management as part of the maintenance procedures. Furthermore, all users and operating systems must be secured, well-maintained, stable, and up-to-date. Lastly, in case a company only uses one domain controller, any unforeseen failure might cause network damage.