Domain controller
A server that manages user accounts, logins, and security policies within an Active Directory domain.
What does it mean Domain controller?
A domain controller is a server that stores the Active Directory directory: users, groups, computers, and policies. It verifies credentials and assigns permissions with every login.
In addition to authenticating logins, it handles Group Policy Objects (GPO) distribution, DNS services within the domain, and time synchronization. It can also be linked to cloud identities in Microsoft 365 via Entra Connect.
Typically, there are at least two controllers in every domain to ensure logins remain functional even if one fails.
Practical examples
A company with 40 employees has two domain controllers and synchronization with Entra ID, so the same user identity is used for logging into computers and Microsoft 365.
Business relevance
The domain controller is the most critical server in the environment. In the event of its failure or infection, logins, folder access, and printing stop; therefore, it must have redundancy and verified backups.
Common mistakes
The most common mistakes include having only a single controller without backup, excessive use of domain administrator accounts, and a lack of directory recovery testing.
How VitalIT helps
At VitalIT, we take care of servers, virtualization, backups, and system monitoring. Learn more on the IT infrastructure page.
Why is this important for businesses?
The domain controller is the most critical server in the environment. In the event of its failure or infection, logins, folder access, and printing stop; therefore, it must have redundancy and verified backups.
Where does this appear in practice?
A company with 40 employees has two domain controllers and synchronization with Entra ID, so the same user identity is used for logging into computers and Microsoft 365.
Most common problems or errors
The most common mistakes include having only a single controller without backup, excessive use of domain administrator accounts, and a lack of directory recovery testing.
Kako pri tem pomaga VitalIT
At VitalIT, we take care of servers, virtualization, backups, and system monitoring. Learn more on the [IT infrastructure](/en/services/it-infrastruktura) page.
Related terms
Related Services
Frequently asked questions
- How many domain controllers do we need?
- At least two, so that logins remain functional even during the failure or maintenance of one.
- Do we need one if we are in the cloud?
- Not necessarily. Smaller companies can use only Entra ID and Intune without a local controller.
- How do we protect a domain controller?
- By using separate administrator accounts, MFA, restricted access, regular updates, and isolated backups.