Microsoft Entra ID, a cloud-based identity and access management service, is comprised of a database (directory) that stores user information and access permissions. Formerly known as Azure Active Directory, it offers a suite of services that facilitate employee authentication and authorization, ensuring that end users can securely access only the IT resources they are permitted to use. These resources encompass both internal assets like corporate intranet data and tools, as well as external resources such as Microsoft 365 and various SaaS applications.
But be sure to note one crucial distinction: Microsoft Entra ID is not merely an adaptation of Active Directory hosted on Microsoft's servers instead of on-premises data centers. Instead, it is a distinct solution integrated into the Microsoft Entra ID public cloud computing platform. However, it's worth noting that on-premises Active Directory and Entra ID can often coexist, forming hybrid AD environments.
Any organization that has a subscription to Microsoft's online business services, like Microsoft 365, it automatically gains access to Microsoft Entra ID. Nevertheless, certain advanced features come at an additional cost. To unlock functionalities such as self-service options, enhanced monitoring, security reporting, and mobile device security, an upgrade to an Entra ID Basic, Premium P1, or Premium P2 license is required.
It’s generally used by three distinct user categories:
The fundamental component that forms the foundation of Entra ID is known as a 'tenant.' An Entra ID tenant represents a dedicated instance of Entra ID tailored to a specific company.
To establish a tenant, your organization can simply enroll in a Microsoft cloud service, such as Microsoft 365, and furnish essential details like your organization's name and location. The initial domain name is constructed by combining the specified name with '.onmicrosoft.com' (e.g., domainname.onmicrosoft.com). The initial domain name is permanent and cannot be altered or removed, but you have the flexibility to incorporate custom domain names, such as companyname.com, into your tenant. Each tenant has a dedicated and trusted Entra ID directory, which includes the tenant's users, groups and apps, and performs identity and access management functions for the tenant’s resources.
Please note that we’re using the word “domain” in the internet sense (a website domain name). It has nothing to do with an on-premises AD domain, which is a group of related users, computers and other AD objects that are managed together. Similarly, Entra ID does not have forests, organizational units (OUs) or other frequent AD structures.
While on-premises Active Directory and Entra ID serve a shared fundamental purpose, it's important to recognize that they represent distinct solutions. Here are some critical points to remember:
Entra ID employs a different approach to authorization than Active Directory. Key components include:
It's certainly feasible to establish a fully cloud-based environment, the prevailing trend among organizations today involves maintaining a hybrid Active Directory environment. The integration is facilitated through the utilization of the Microsoft tool Entra ID Connect, which synchronizes identity data from the on-premises AD to Entra ID. Consequently, users can employ their on-premises credentials to authenticate access to cloud resources such as Teams, SharePoint Online, and SaaS-based applications like Dropbox, Google Apps and Amazon Web Services (AWS).
On the backend, IT professionals primarily handle user management, group administration, and permissions within on-premises Active Directory. Any modifications made are automatically synchronized with the cloud. This approach mitigates the challenge of managing two entirely distinct sets of identities and permissions, a task prone to considerable difficulty and error.
Yet it's crucial to acknowledge that not all aspects can be stored and managed within the on-premises Active Directory. For example, cloud-only objects and attributes come into play, including:
Cloud-specific User Accounts: Organizations typically establish Business-to-Business (B2B) and Business-to-Consumer (B2C) accounts in Entra ID for external users. For example, invitations sent to business partners or consultants result in the federation of their external identities into Microsoft Entra ID, creating an account that exists exclusively in the cloud and not in the on-premises AD.
Cloud-specific Attributes: Certain attributes, such as the "license type," are exclusive to the cloud. Every user in the on-premises AD permitted to use Office 365 applications possesses this attribute, determining their entitlement to specific features. In the event of a user object deletion, recovery of the on-premises AD user object via Entra ID Connect synchronization may occur. However, the cloud-only attribute, like the license type, would be lost, rendering the user unable to operate in Office 365 until the issue is manually addressed.
Consequently, even in a hybrid AD environment, exclusive reliance on on-premises management, security, migration, and reporting solutions is insufficient, emphasizing the need for a comprehensive approach that encompasses both on-premises and cloud-based considerations.
These resource pages offer additional detail about Microsoft Entra ID and its role in hybrid Active Directory: