What is a network domain?

A network domain is a system of interconnected network objects, systems, and resources that are centrally managed. You can then use policies to enforce settings and configurations, which can be applied throughout the domain. 

A network domain is a collection of interconnected devices, such as computers, printers, and servers, as well as network objects, such as users, groups, and systems. These devices and objects are organized and managed under one administrative umbrella. Domains also govern mechanisms such as authentication and resource access. You can use policies to enforce settings and configurations, which can be applied throughout the domain. 

To understand network domains, consider the definitions of the words “network” and “domain.” A network is a system of interconnected things, and a domain is a set of assets or items controlled by an authority or set of rules. 

 A network domain may consist of any or all of the following: 

• Computers 

• Security groups 

• User objects 

• Servers 

• Printers 

• Internet of things (IoT) devices 

 In a Windows Active Directory domain, all devices within a domain are governed by Group Policy. This set of standards may be managed in several ways. Windows environments use a domain controller.

What is a domain controller?

A domain controller is a domain member server with specific roles that manages logins, user and device authentication, access, and network security for a domain. The domain controller is like a referee, enforcing the rules for how items in the network connect and share information.   It’s common for domain controllers to also function as domain name system (DNS) servers. Users can access the server and other network resources using their unique domain names because DNS translates between those names and their IP addresses. In Windows environments, the following Flexible Single Master Operation (FSMO) roles are designed to manage replication and avoid replication conflicts:  

• Schema master  

• Domain naming master 

• RID master 

• PDC emulator 

• Infrastructure master 

Domain controllers and Active Directory

Domains rely on specialized servers called domain controllers, which handle authentication requests and provide access to authorized network resources.

Domain controllers store and interact with directory services. A directory service is a database that stores and organizes information about network resources, objects, and attributes. While Microsoft's Active Directory is not the only directory service, it is by far the most commonly used among enterprises and is included with Windows Server operating systems.

What are examples of network domains?

Since network domains come in different shapes, sizes, and architectures, there are endless potential combinations for examples. Here are a couple of common scenarios:  

A simple, company-wide network domain: Smaller businesses often have a single network domain for their entire operation. All users defined by the domain controller may have access to the printers, phones, and other essential devices, but access to other resources might be more limited. Users may be granted permission to access domain resources remotely.

An enterprise-level network domain: A large company may have multiple domains. These domains can be configured to allow resources to communicate across domains using trust relationships. Each network domain could correspond to separate sections of the system, types of services, or service regions.

How does a network domain work?

Domain controllers manage resource access, authentication, and replication. Objects can be created on the domain, such as user accounts and security groups. Computers and other devices with LDAP functionality can be added to the domain, which are then managed by the domain policies and systems. 

An individual computer not connected to a network domain is controlled by its owner or user, who determines settings and accounts. In contrast, a computer connected to a network domain has its accounts and settings determined by the domain controller or device management system. Out-of-the-box users can still manage every user-side non-admin setting. When a user logs into a computer on the domain, the system authenticates their credentials. This functionality also makes it possible for users to log into their accounts from different devices and have access to the same files and resources.  

The main idea behind a network domain is to create structure, improve security, and permit high-level control over all connected physical assets and digital resources.

LAN vs. WAN network domains

A local area network (LAN) refers to a network of computers and devices in a localized area. These devices may be in the same room or the same building, or several localized buildings, such as a college campus. A wide area network (WAN) refers to a network of computers and devices that are geographically spread out. A WAN network may include devices in different buildings, cities, or even countries. Smaller network domains, such as small businesses, primarily utilize a LAN configuration. Larger network domains often utilize both these networking configurations.

Domains vs. workgroups in Active Directory

A network domain is distinct from a workgroup — which is a group of connected computers — because a single authority manages a network domain’s configuration and controls. With a workgroup, each computer is an independent entity that can simply access and communicate with other connected devices.

Think of a workgroup as the equivalent of playing a tennis match with a friend. With so few participants, you can generally expect everyone to behave, follow the rules, and treat resources with respect. However, if you invite a lot of players to a tournament, you need a referee to enforce the regulations. Otherwise, some rogues may break the rules, smash their tennis rackets, and steal the net to wear as a victory cape. Just as a referee keeps things running smoothly on the court, a network domain keeps connected computers in line.