People use Active Directory when they log in to their work machines and when they access apps, printers, and file shares. But the primary users of Active Directory are the admins. These people actually operate, manage, and configure AD. AD admins likely include all of the IT team and may also include members of the security, DevOps, or engineering teams.
Virtually all organizations around the world use a solution such as Active Directory or other identity provider. Enabling and controlling access to IT resources is one of the most important aspects of operating an organization in modern times. Solutions such as directory services enable organizations to be productive. AD is in place at almost every large organization and many small ones. In short, a directory service is what connects users to their IT resources, and AD has done that for users to their Windows resources for almost two decades.
Looking for a more in-depth answer? We also have a full blog covering why AD is important. Objects can include users, laptops, servers, and even groups of other objects explained below. AD enables admins to manage sets of multiple objects and these sets are known as groups. Using GPOs group policy objects , an admin can make a change on one group and have that change apply to all objects within that group.
A forest describes a collection of trees, which denote a collection of domains. So, what are trees and domains? Well, a domain is a collection of users, computers, and devices that are part of the same Active Directory database.
If an organization has multiple locations, they may have a seperate domain for each one. For example, an international organization could have a domain for their London office, another one for their New York office, and a third one for their Tokyo office. A tree could be used to group all three of those domains as branches belonging to the same tree, so to speak. An organization that has multiple trees could then group them into a forest.
This is a core concept of Active Directory and can be complicated. A domain controller is any server that is running Active Directory Domain Services. At least one domain controller is necessary to use Active Directory, though most organizations have at least two per location. Large, multinational organizations may require dozens of domain controllers across each of their physical locations in order to ensure high availability for their AD instance. Generally, DCs are thought of being tied to a physical office, which in the current remote work environment can be challenging.
Individual users and their systems are connected to the domain controller through the network. When users request access to objects within the Active Directory Database, AD processes that request and either authorizes or prevents access to the object. The authentication and access occurs seamlessly. But this concept begins to fall apart as non-Windows resources are introduced. It also struggles if users are remote and not physically attached to the domain — in this case, the end user will need to VPN into the network and be authenticated by the DC in order to gain access to their on-prem, Windows-based resources.
Note that Microsoft has also extended the concept of a domain to Azure. This domain is separate and distinct from the on-prem domains, although the two can be bridged through a variety of connective technology including Azure AD Connect and Azure AD. We should also note that there is a new concept called the Domainless Enterprise , which is taking the approach of eliminating the domain concept, but still retaining the idea of securely and frictionlessly accessing IT resources wherever they may be.
This concept is especially helpful for organizations that leverage web applications, cloud infrastructure, and non-Windows platforms e. When Active Directory Domain Services is installed on a server, it becomes known as a domain controller. This server stores the Active Directory Database, which contains a hierarchy of objects and their relationship to one another.
Keep in mind that a domain is a management boundary. The objects for a given domain are stored in a single database and can be managed together. A forest is a security boundary. Objects in different forests are not able to interact with each other unless the administrators of each forest create a trust between them.
For instance, if you have multiple disjointed business units, you probably want to create multiple forests. The Active Directory database directory contains information about the AD objects in the domain. Common types of AD objects include users, computers, applications, printers and shared folders.
In particular, organizations often simplify administration by organizing AD objects into organizational units OUs and streamline security by putting users into groups. These OUs and groups are themselves objects stored in the directory. Objects have attributes. Some attributes are obvious and some are more behind the scenes.
Databases are structured, which means there is a design that determines what types of data they store and how that data is organized.
This design is called a schema. It's usually trivial to move these roles around, so while some DCs do slightly more than others, if they go down for short periods of time, everything will usually function normally. If they're down for a long time, it's easy to transparently transfer the roles. Replication, of course. By default, DCs belonging to the same domain in the same site will replicate their data to each other at 15 second intervals. This makes sure that everything is relatively up to date.
There are some "urgent" events that trigger immediate replication. These events are: An account is locked out for too many failed logins, a change is made to the domain password or lockout policies, the LSA secret is changed, the password is changed on a DC's computer account, or the RID Master role is transferred to a new DC. Any of these events will trigger an immediate replication event. Password changes fall somewhere between urgent and non-urgent and are handled uniquely.
If a user's password is changed on DC01 and a user tries to log into a computer that is authenticating against DC02 before replication occurs, you'd expect this to fail, right? Fortunately that doesn't happen. When DC01 is updated with the user's new password, that change is immediately replicated to DC03 also. When thee authentication attempt on DC02 fails, DC02 then forwards that authentication attempt to DC03 , which verifies that it is, indeed, good, and the logon is allowed.
DNS is critical to a properly functioning AD. The official Microsoft party line is that any DNS server can be used if it is set up properly. Your clients should all be configured to use your AD DNS servers, so it's important to have redundancy here. If you have two DCs, have them both run DNS and configure your clients to use both of them for name resolution.
Also, you're going to want to make sure that if you have more than one DC, that they don't list themselves first for DNS resolution. This can lead to a situation where they are on a "replication island" where they are disconnected from the rest of the AD replication topology and cannot recover. If you have two servers DC01 - Because once you know what you're doing, you life becomes infinitely better. AD allows for the centralization of user and computer management, as well as the centralization of resource access and usage.
Imagine a situation where you have 50 users in an office. If you wanted each user to have their own login to each computer, you'd have to configure 50 local user accounts on each PC.
With AD, you only have to made the user account once and it can log into any PC on the domain by default. If you wanted to harden security, you'd have to do it 50 times. Sort of a nightmare, right? Also imagine that you have a file share that you only want half of those people to get to.
If you're not using AD, you'd either need to replicate their username and passwords by hand on the server to give seemless access, or you'd have to make a shared account and give each user the username and password. One way means that you know and have to constantly update users' passwords.
The other way means that you have no audit trail. Not good, right? You also get the ability to use Group Policy when you have AD set up.
For example, if you want to make it so that "Shutdown" isn't on the start menu for lab PCs, you can do that in one setting in Group Policy. Instead of spending hours or days configuring the proper registry entries by hand, you create a Group Policy Object once, link it to the correct OU or OUs, and never have to think about it again.
There are hundreds of GPOs that can be configured, and the flexibility of Group Policy is one of the major reasons that Microsoft is so dominant in the enterprise market. Note: This answer was merged into this question from a different question that asked about the differences between forests, child domains, trees, sites, and OUs.
This was not originally written as an answer to this specific question. You want to create a new forest when you need a security boundary. For example, you may have a perimeter network DMZ that you wish to manage with AD, but you don't want your internal AD available in the perimeter network for security reasons.
In this case, you would want to create a new forest for that security zone. You may also want this separation if you have multiple entities that do not trust each other - for example a shell corporation that encompasses individual businesses that operate independently. In this case, you'd want each entity to have its own forest. Really, you don't need these any more.
There are few good examples of when you would want a child domain. A legacy reason is because of different password policy requirements, but this is no longer valid, as there are Fine-Grained Password Policies available since Server You really only need a child domain if you have areas with incredible poor network connectivity and you want to drastically reduce replication traffic - a cruise ship with satellite WAN connectivity is a good example.
In this case, each cruise ship may be its own child domain, so as to be relatively self-contained while still being able to leverage the benefits of being in the same forest as other domains from the same company. This is an odd-ball. New trees are used when you want to maintain the management benefits of a single forest but have a domain in a new DNS namespace. Instead, I will provide a basic summary of the steps required to install AD, which should at least point you in the right direction.
Assuming you already have Windows Server installed, you will need to…. Once you have Active Directory Domain Services installed, you will then need to configure your installation, which includes changing default passwords, setting up OUs, domains, trees, and forests.
As mentioned, a detailed explanation of setting up and configuring Active Directory is beyond the scope of this article. For detailed up-to-date instructions, you will need to consult the official documentation. Given that increasingly more organizations are shifting their business operations to the cloud, Microsoft has introduced Azure Active Directory Azure AD , which is their cloud-based version of Windows AD, which can also sync with on-premise AD implementations.
Azure AD is said to be the backbone of Office and other Azure products; however, it can also be integrated with other cloud services and platforms. Some of the differences between Windows and Azure AD are as follows. One of the main reasons why you might want to use Windows AD is if you are storing large amounts of valuable data and have a team of experienced IT professionals managing your cybersecurity program.
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