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The Difference Between a Domain and a Domain Controller

Nishat from Bangladesh writes:

What is the difference between a domain and a domain controller? Can you please explain?

Networking terminology can be quite confusing, especially for individuals who don’t have a degree in computer science or networking. One of the main reasons for the confusion is that some of the terms have other meanings in the computer world. For example, the term domain, which applies to a network of computers, is also used as slang for an Internet domain or domain name server. While domains and domain name servers are completely different entities, referring to them by the same name confuses many people.

In terms of networking, a domain is a group of connected computers that can be accessed from a central server or servers. All the computers within a specific domain share a common set of security rules; however, individual users can be granted specific rights within the domain. The term domain is typically only used when discussing Windows-based networking and is set up using Active Directory on Windows-based machines.

The term domain controller is used to denote a computer within the domain that controls the rest of the computers in the domain. From the domain controller, a network administrator can access networked computers, create or delete accounts, or manage privileges and security. In many networks, the file server and domain controller are one in the same, but this is not a requirement. Although a domain controller can be quite helpful, especially when dealing with larger domains, it is not required. There are both advantages and disadvantages to using a domain and domain controller, so it’s up to the network administrator to determine whether the use of a domain and domain controller is beneficial for your network.

Advantages of Using a Domain and Domain Controller

When a network has hundreds or thousands of networked computers, a domain is necessary to connect them. Although a domain controller is not absolutely required, it makes it easier for administrators to diagnose problems, create new accounts and modify permissions. Without a domain controller, someone would have to physically go to each computer to accomplish these tasks. This would be an impossible task if the computers within a domain were located in different physical locations. When managing file permissions on one or more servers or computers without using a domain controller, the network administrator would have to create the permission sets on each of the computers that would be sharing files and edit all of them any time there are changes. This can be quite time consuming, which is why it’s beneficial to set up a domain and use a domain controller.

Disadvantages of Using a Domain and Domain Controller

Generally speaking, smaller networks do not need to bother with domains or domain controllers, especially when all the computers are located within one physical location. Permissions and accounts can easily be handled on smaller networks without the hassle of a domain controller. Networks of computers that do not use a domain controller are often referred to as peer-to-peer networks and permissions and accounts are set up on each computer within network. When using a peer-to-peer network, each user needs to have an account set up on each computer he uses, whereas with a domain and domain controller, a user can log into any user within the domain using his password.

Another downside to setting up a domain is that not all operating systems are designed to connect to a domain. Unix and Linux-based systems, for example, cannot connect, and some companies have programs that require these operating systems to run. The Windows XP operating system was also not designed to connect to a domain. Although there are workarounds for Windows XP machines, it is just one more hassle for a network administrator to deal with.

Hope that helps!

~Chad Stetson