The Domain Controller
There are many different kinds of networks, Internet, Cisco, Workgroup, or Domain. The last two are Microsoft types, where one does not do authentication or network management, but the other one does both.
The WorkGroup network is a peer-to-peer type of network that has no central computer that acts like a network manager. Each computer can interact with the others provided that they are on the same subnet. If so, they can share files or network devices like printers.
A Domain Controller, on the other hand, is a computer that manages the network in several ways. One way is security. That means that users can only access the network if they have permission through a login and password account. Another way is through computer control. This means that only certain devices can be part of the computer network. Adding a computer to the network means that controls on it come by way of the domain controller.
The computer domain presents a collection of computers that are governed and controlled by the Domain Controller, a central server. This server has certain responsibilities to make sure the network is operating properly.
The DNS Server
One of the functions of the Domain Controller is that network names and the IP addresses are resolved properly. This is like a phone book.
A phone book will have three columns, the name, the address, and the phone number (in the white pages). To find a phone number you look up the name first and then the phone number will be on the same row. In computer operations this is called name resolution.
In a computer network, communication occurs via an IP address. This is a 32 bit binary number that is broken up into four octets. For example, 192.168.15.200 is an IP number. If we convert that to binary it becomes:11000000. 10101000. 00001111. 11001000.
That is not easy to remember, but the number in Dec is easier to remember, but even easier is the name, which we can say is DC-1. With name resolution we can associate an IP address with a computer. That is what the DNS server routinely does.
The other job the DNS server does is point a computer toward the Internet, or to a computer inside a network that point towards the Internet.
Once the DNS server is configured the next server that must be on a Domain Controller is a DHCP server.
The DHCP Server
The DHCP server performs leasing operations. DHCP stands for Dynamic Host Configuration Protocol. It takes a group of IP addresses that have been created for the network and hands them out to computers that are joining the network. They are leased because, normally, the handout lasts 72 hours, and then it expires. However, it is typically renewed, so the same computer will receive the same IP address.
The other items that a DHCP server provides are the gateway, the subnet mask, and the IP address that belongs to the current DNS server, even if it belongs to the Domain Controller itself.
The gateway is a route to another network or to the DNS server. The subnet mask is a binary set of numbers that helps define what network the IP address belongs to.
The Active Directory Server
With these tools in hand, the Active Directory is implemented on the Domain Controller and is used as the (software) manager on the computer. By contrast, the hardware manager would be the switch or router on the network. Using the DHCP server with the DNS server in conjunction, in the Domain Controller, lends to network management.
The Active Directory tool is used for a variety of different management functions. One function is to define who enters the network, both as a user or as a computer. Users are given login names and passwords and memberships to certain groups, like the administrators group. Computers are controlled with the DHCP server.
Another function involves Organizational Units. These are units where individuals are put into to control what they can and cannot access. So a user might be a part of the sales group, but not part of the finance group. In this matter this will specify the security towards the network. You can also control when a user can have access to the network.
Summary - Windows Server 2003 Tutorial
In this short Windows Server 2003 tutorial we saw that Server 2003 is a network manager that can function like a domain controller. It uses the controls of DHCP, DNS, and Active Directory to manage the network from the software side. This control makes the network manageable in terms of the users, and computers, and the security privileges that are presented. It controls who can access the network, when, and what privileges are available.