Active Directory Domain Services - Tutorial, Definitions & Overview

Active Directory Domain Services (AD DS) is nothing but a core function in Microsoft’s Active Directory, through which users can build a centralized, well-integrated, and scalable Windows network.

System admins can store, monitor, and manage application data and resource information in a systematic hierarchy structure. This logical structure comprises the AD forest, its Domains, and their respective Organizational Units (OUs).

Admins can efficiently handle a network’s users and computers and organize them into a distributed database. Moreover, AD DS also features security integrations such as limiting access to directory resources, SSO, LDAP, authorizing logins, security certificates, and rights management.

To understand AD DS better, let’s first look into IAM (Identity and Access management) thoroughly.

What is IAM?

The launch of the LDAP protocol really turned the tables for the IAM industry, as it served for two giants viz.

OpenLDAP and Microsoft Active Directory solutions along with other smaller ones. Both these solutions became widely popular amongst enterprises across the globe as reliable identity providers.

What Exactly Does an Identity Provider Do?

Identity providers do the job of creating a well-integrated central store for an organization’s users and data.

In the IdP, all the user accounts are securely stored along with resource information. The resources are interrelated to the user identities that utilized them.

Not just that, the resources such as networks, applications, systems, etc. are also restrained for a specific user based on their role.

For Active Directory Domain services, this process was carried out for Windows-based networks and resources. As a user logs-in into their computer, the AD DS would provide access to resources that the user needs and is authenticated to use.

What is Active Directory?

Active Directory is Microsoft’s technology to be used in Windows Server space. It is a logical hierarchy structure that is able to share database information to secure, manage, and easily locate the device and network resources.

Not only does it offer full-scale authorization and authentication core functions, but also provides a framework for numerous other services. AD makes use of Windows Servers OS and it is an LDAP database in itself containing networked elements.

To offer directory services to large-scale, complex environments, Active Directory was readily introduced in Windows 2000.

The first and foremost role of AD is to authenticate users in the domain network. AD stores objects such as computers, groups, file shares, file permissions, printers, and group policies.

Plus, it also centralizes security elements as all the users’ accounts and their respective passwords are stored in a single location.

IT admins can create, restrict or remove users, set up group policies, and even allow users to change their passwords. All of these functions determine how users will interact in the domain environment.

In short, AD DS is a well-integrated, centralized framework for domain management. Each domain becomes an element of Active Directory Forest, but it can also have more than one domain systematically organized into logical units.

Without AD, admins will have to create local users on every computer and reset passwords for each one of them on their PC.

Types of Active Directory Objects:

Active Directory Objects can be differentiated into two types:

Container Objects
These are the main objects that also consist of other objects within them such as Domains, Forests, Trees, and Organizational Units.
Leaf Objects
These objects do not comprise other objects inside them, for example, computers, printers, peripheral devices, users, etc.

Key Elements of Active Directory Domain Services:

Active Directory Domain Services comprise of:

Global Catalog
Consists of information regarding directory objects. With this, system admins and users can easily find the directory information, no matter which domain it is contained within. For example, user names, contacts, and so on.
Schema
Is a set of rules defining classes of objects and their properties stored in the directory along with the format of their names and limits on objects’ instances.
Query and Index mechanism with the help of which network users can easily publish or find objects and their attributes in the AD.
Replication service includes the distribution of directory data across a network. This replication is carried out by domain controllers within a domain, each having a copy of directory data for their domain. Any changes done to the directory information is automatically replicated to domain controllers within a domain, thus they have the same catalog and schema. AD makes use of multiple domain controllers for fault tolerance, the balance of the load, and other crucial reasons. For this, every domain controller within a domain needs to have a copy of its AD database. This is where the replication service comes in. Know that domain controllers from different domains shall not replicate to one another.
Sites: This is the representation of Windows’ network topology.
Lightweight Directory Access Protocol (LDAP): LDAP is a protocol which allows the AD to communicate with other LDAP-based directory services within the network.

Which Services are included in Active Directory Domain Services?

AD DS consists of various services such as:

Domain Services:
These are core services which handle data centralization, manage login authentication, search functionality and allow seamless communication between users within a domain.
Lightweight Directory Services:
These services provide support for directory-enabled applications with the help of the LDAP protocol.
Rights Management:
This feature is all about information rights such as restricting access to personal information of users and encrypting confidential data.
Directory Federation Services:
DFS offers SSO (Single-Sign-On) functionality to the users for safe authentication. This feature is most helpful when communicating with multiple web applications in a single session.
Certificate Services:
This feature lets you create, share and manage security certificates. These certificates ensure security and privacy by encrypting data sent across the network.

Role of Domain Controllers in Active Directory Domain Services:

Basically, a domain controller (DC) is nothing but a server in the Windows network that provides user access to domain resources. Its main objective is to authorize and authenticate users in a network based on their names and passwords.

Domain Controllers hosts AD DS as well as other services such as:

NetLogon:
Its aim is to authenticate the login credentials of users in the domain network.
KDS:
Kerberos Key Distribution Center is a service used to issue, authenticate, and carry out the encryption of Kerberos tickets. It will authenticate users when using the Kerberos protocol. The service features TCS (Ticket Granting Server) and an Authenticating Server.
IsmServ (Intersite Messaging):
This service assists the exchange of data between PCs in a Windows networked environment.
W32time service:
Windows time or W32time service utilizes NTP (Network Time Protocol) for syncing date and time for all PCs within a networked domain. The clock synchronization on computers is important for Kerberos to work properly.

Installing Active Directory Domain Services

Let’s see a quick tutorial on how to install Active Directory Domain Services on Windows Server:

Opening Server Manager: Press the “Windows” icon on your keyboard and type “Server Manager” in the search box. The application will open.
Adding Roles and Features: In the Server Manager window, right-click on “Manage” and select “Add Roles and Features” option. Once the wizard opens, click on “Next”.
Select Installation Type: Clicking “Next” will open the Installation Type window where you need to select “Role-based or feature-based installation” option. Then click on “Next”.
Server Selection: Here comes the “Server Selection” click on the server you want to install AD DS on and then click on “Next”.
Server Roles: In this window, you will see many “Roles” options. Tick on “Active Directory Domain Services”.
Add Features: Right after, the “Add Roles and Features” wizard will open up. Click on the “Add Features” button and then hit “Next”.
Select Features: Immediately the “Select Features” section will open up. Simply click on “Next”.
Installation of AD DS: Now the main window of AD DS installation opens, click on “Next”.
Confirmation Window: Confirmation window displays what all will be installed on the server. Once you read it all, click on “Install”.
Promote to Domain Controller: After installation, go to “Server Manager” and you will see a yellow triangle notification icon right beside the “Manage” tab. Click on it and choose “Promote this server to a domain controller”.
Add a New Forest: This will open AD DS Configuration Wizard. Click on “Add a new forest” and type your enterprise’s root domain name and hit “Next”.
Domain Controller Options: On the next page, keep all the default boxes checked and type in your DSRM password. Click “Next”.
DNS Options: In the DNS Options page, you might see an error message on the top. Ignore it and hit “Next”.
NetBIOS domain name: Here you can change the domain name or leave the default name as it is. Hit “Next”.
Paths: Keep paths defaults as it is, and click “Next”.
Review Selections: In this page, check all the options you’ve selected so far, and hit “Next”.
Prerequisites Check: In this window, all the prerequisites will be validated before the installation of AD DS. If any errors pop up, look at previous steps, and fix them. Click “Install”.
Once done, your server will reboot and then you will be able to log into the domain with DSRM password input you’ve set up in step 12.

Wrap Up:

Active Directory Domain Services is one of the best terminologies used to enhance the Windows server and make it stand out in enterprises.

It seamlessly adapts with the majority of Microsoft solutions, making it easier for users to do their operations. As you install AD DS, you can easily manage it through the Active Directory Administrative Center. Hope this guide was insightful for you to read!